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1

Exciting Students About Science & Engineering ...  

E-print Network

applications include nanomachines, bioimplants, smart materials, fuel cells, genetic engineering and spaceExciting Students About Science & Engineering ... ASM MATERIALS CAMP® 2013 MATERIALS IN TODAY'S WORLD Materials science and engineering is a study of the relationship between the structure

Evans, Paul G.

2

Communicating the Excitement of Science  

SciTech Connect

In this talk (which will include some exciting science) I will discuss some lessons I have learned about communicating science to scientists (in my own field and others), students, the public, the press, and policy makers in giving 500+ colloquia and seminars, 300+ public lectures and many informal presentations (including cocktail parties).

Michael Turner

2009-06-05

3

Communicating the Excitement of Science  

ScienceCinema

In this talk (which will include some exciting science) I will discuss some lessons I have learned about communicating science to scientists (in my own field and others), students, the public, the press, and policy makers in giving 500+ colloquia and seminars, 300+ public lectures and many informal presentations (including cocktail parties).

Michael Turner

2010-01-08

4

RXTE Observations of Cas A  

NASA Technical Reports Server (NTRS)

The exciting detection by the COMPTEL instrument of the 1157 keV Ti-44 line from the supernova remnant Cas A sets important new constraints on supernova dynamics and nucleosynthesis. The Ti-44 decay also produces x-ray lines at 68 and 78 keV, whose flux should be essentially the same as that of the gamma ray line. The revised COMPTEL flux of 4 x l0(exp -5) cm(exp -2)s(exp -1) is very near the sensitivity limit for line detection by the HEXTE instrument on RXTE. We report on the results from two RXTE observations - 20 ks during In Orbit Checkout in January 1996 and 200 ks in April 1996. We also find a strong continuum emission suggesting cosmic ray electron acceleration in the remnant.

Rothschild, R. E.; Lingenfelter, R. E.; Heindl, W. A.; Blanco, P. R.; Pelling, M. R.; Gruber, D. E.; Allen, G. E.; Jahoda, K.; Swank, J. H.; Woosley, S. E.; Nomoto, K.; Higdon, J. C.; Dermer, Charles D. (Editor); Strickman, Mark S. (Editor); Kurfess, James D. (Editor)

1997-01-01

5

How to Generate Student Excitement in Science  

ERIC Educational Resources Information Center

To successfully generate student excitement in science, teachers need to be flexible regarding their curriculums. Students also need to be open to novel, hands-on experiences. This article describes a student teacher (ST) who taught a science unit on "Our Environment." She had already prepared her lesson and unit thoroughly but she changed the…

Ediger, Marlow

2005-01-01

6

Exciting careers blending engineering, science, and ecology  

E-print Network

Exciting careers blending engineering, science, and ecology New Opportunities Making the world://bee.oregonstate.edu/ecoe Ecological Engineering is: · Ecosystem restoration and habitat design at multiple scales · Watershed · Phytoremediation and bioremediation · Industrial ecology · Constructed wetlands and tidal marshlands · Mitigation

Tullos, Desiree

7

There's Nothing More Exciting than Science  

ERIC Educational Resources Information Center

The basic contention that a more imaginative, creative, and challenging approach will result in better achievement in SATs--in other words, if the children enjoy their science they will do better--was the basis of a project at Oxford Brookes University. The project was devised to encourage and enable the participating teachers to develop a…

Wilson, Helen; Mant, Jenny; Coates, David

2004-01-01

8

Computer Science Programs Available at FAU's Treasure Coast Campus Florida Atlantic University's College of Engineering and Computer Science offers exciting  

E-print Network

Computer Science Programs Available at FAU's Treasure Coast Campus Florida Atlantic University's College of Engineering and Computer Science offers exciting degree programs in computer science.I.E.T.) and bachelor in computer science. The innovative B.I.E.T. degree program provides more hands-on, practical

Fernandez, Eduardo

9

RXTE Observation of the Tycho Supernova Remnant  

NASA Technical Reports Server (NTRS)

SN1006 [4] and Cas A [1, 9] supernova remnants have been shown convincingly to have a hard X-ray power-law continuum. This continuum is thought to be the synchrotron radiation from accelerated electrons of approx. 100 TeV at the shock fronts. Our goal of AO2 RXTE observation is to detect the hard X-ray continuum and to determine the nature of the continuum from Tycho SNR. A detection of a power-law continuum from Tycho SNR can strongly argue for SNRs are the source of cosmic rays with the first order Fermi acceleration as the energizing process. We report the results of our AO2 RXTE 1 x 10(exp 5) sec observation of Tycho SNR. We detect two components of the X-ray spectrum from Tycho SNR both at better than 3 omega confidence. The best two component models are: bremsstrahlung (kT=2.67 +/- 0.13 keV) + bremsstrahlung (kT=7.07 +/- 2.21/1.72 keV) or bremsstrahlung (kT=2.36 +/- 0.21/0.57 keV) + power-law (gamma=2.58 +/- 0.12/0.09 ). This result is an improvement compaxed with the previous most sensitive X-ray measurements by Ginga which shows Tycho's observed X-ray continuum requires a two-component model to yield acceptable fits with the hard component parameters being highly uncertain. Our RXTE measurements constrain all parameter within 3o, ranges. However, we cannot yet distinguish between thermal and nonthermal models for the hard component. In the followings, we describe what we accomplished in the period covered by the grant proposal.

The, Lih-Sin

1998-01-01

10

Highlights of RXTE Studies of Compact Objects after ~5 Years  

E-print Network

Observations with the Rossi X-ray Timing Explorer (RXTE) have led to fundamental progress in the study of compact objects, in particular neutron stars and black holes. In this paper we present briefly some highlights from ~5 years of RXTE operations.

H. Bradt; R. Rothschild; J. Swank

2001-06-27

11

More Science Activities. 20 Exciting Experiments To Do!  

ERIC Educational Resources Information Center

Science and technology affect every facet of human life. By the 21st century, society will demand that all of its citizens possess basic competencies in the fundamentals of science and the use of technology. As science increasingly becomes the dominant subject of the work place, it is important to begin developing within children an understanding…

Smithsonian Institution, Washington, DC.

12

Still More Science Activities. 20 Exciting Activities To Do!  

ERIC Educational Resources Information Center

Science and technology affect every facet of human life. By the 21st century, society will demand that all of its citizens possess basic competencies in the fundamentals of science and the use of technology. As science increasingly becomes the dominant subject of the work place, it is important to begin developing within children an understanding…

Smithsonian Institution, Washington, DC.

13

Excite  

NSDL National Science Digital Library

Hot on the heels of AltaVista's Raging Search (see the May 5, 2000 Scout Report) comes another returned and (somewhat) slimmed-down search engine that focuses on relevant results. Like Raging Search, Excite's new Precision Search uses Google-style link analysis technology ("Deep Analysis") to help identify the most useful sites. Test queries produced consistently relevant results among the top few returns, though an indication of the number of total returns would be helpful, with two banner ads and (in some but not all cases) a Quick Results box on the left that could be quite handy for consumer-related searching. For instance, a search for "Plymouth" yielded links to research and comparisons, blue book values, financing, and service and repair information in the Quick Results box. I was also pleased to see that clicking on one of the other search categories (category, news, photo, audio/video) instantly produces returns for the original query, though the photo databases available seem somewhat limited compared to, say, AltaVista. While users searching for "official" sites will still do best at Google, those who also search for additional resources such as news, photos, and audio/video content may wish to give Excite Precision a run-through.

14

RXTE Observations of Several Strong Flares from the TeV Blazar 1ES 1959+650  

NASA Technical Reports Server (NTRS)

Responding to the RXTE Cycle 7 NASA Research Announcement, we proposed to use the RXTE X-ray telescopes to intensively observe the TeV Gamma-ray Blazars Markarian 421, Markarian 501, 1ES 1959+650 and 1ES 1426+428, when their X-ray or TeV Gamma-ray fluxes would surpass preset trigger thresholds. In May and June, 2002, the Blazar 1ES 1959+650 (z=0.048) showed a series of spectacular X-ray and gamma-ray flares. Following the detection of a strong Gamma-ray flare on May 16 and 17 with the VERITAS 10 m Cherenkov Telescope, we invoked intensive RXTE observations, as well as complementary radio, optical and GeV/TeV Gamma-ray observations. From May 18 to August 14, more than 150 ksec RXTE observations were taken, yielding a unique data set with simultaneous RXTE and GeV/TeV Gamma-ray coverage.We used the financial support from the ADP program of NASA s Office for Space Science to perform a comprehensive analysis of the RXTE data. We studied in detail the temporal and spectral characteristics of the source. We collected multiwavelength data from a large number of collaborators, and performed a detailed cross-correlation analysis. Eventually, we interpreted the results in the framework of a Synchrotron-Self Compton model. The most important discovery of our research has been the detection of an orphan gamma-ray flare , not associated with an X-ray flare. The discovery showed conclusively that most models invoked to describe the non-thermal emission from blazars are overly simplistic.

Krawczynski, Henric

2004-01-01

15

RXTE Observations of MAXI J1836-194  

NASA Astrophysics Data System (ADS)

RXTE observed the recently discovered X-ray transient MAXI J1836-194 (Atel #3611, #3613, #3614) beginning at 11:08:01 (UT) on August 31, 2011, for a total of 6 ksec of good exposure over two RXTE orbits. We detect the source at a count rate of approximately 140 cts/sec (1PCU), and variability is evident with the eye. A power spectral study shows significant flat-topped, band-limited noise breaking to a power-law below 5 Hz with evidence for a weak QPO at 0.5 Hz, above the break.

Strohmayer, T. E.; Smith, E. A.

2011-08-01

16

RXTE Observation of PSR B0656+14  

E-print Network

PSR B0656+14 was observed by the {\\it Rossi X-ray Timing Explorer (RXTE)} with the proportional counter array (PCA) and the high-energy x-ray timing experiment (HEXTE) for 160 ksec during August 22 -- September 3, 1997. No pulsation was firmly found in the timing analysis, in which the contemporaneous radio ephemeris and various statistical tests were applied for searching evidence of pulsation. A marginal detection of pulsation at a confidence level of 95.5% based on the $H$-test was found with data in the whole HEXTE energy band. In the energy band of 2-10 keV the {\\it RXTE} PCA upper limits are about one order of magnitude lower than that from {\\it ASCA} GIS data. If the {\\it CGRO} EGRET detection of this pulsar is real, considering the common trait that most EGRET-detected pulsars have a cooling spectrum in hard x-ray and gamma ray energy bands, the estimated {\\it RXTE} upper limits indicate a deviation (low-energy turn-over) from a cooling spectrum starting from 20 keV or higher. It in turn suggests an outer-magnetospheric synchrotron-radiation origin for high-energy emissions from PSR B0656+14. The {\\it RXTE} PCA upper limits also suggest that a reported power-law component based on {\\it ASCA} SIS data in 1-10 keV fitted jointly with {\\it ROSAT} data, if real, should be mainly unpulsed.

Hsiang-Kuang Chang; Cheng Ho

1998-08-11

17

RXTE Timing of New Energetic Pulsars for Glast (core Program)  

NASA Astrophysics Data System (ADS)

GLAST is expected to detect many new gamma-ray pulsars, and hopefully solve problem of unidentified gamma-ray sources. However, detecting pulsars requires phase-coherent monitoring to provide a pulse ephemeris with which to fold the gamma-ray data. This is because of the paucity of gamma-ray photons, which demands ~year long integration times, coupled with the timing noise and glitches seen in the best GLAST targets. For radio-quiet pulsars, regular RXTE monitoring is the only practical option for coherent timing. We propose to time any radio- quiet energetic young X-ray pulsar discovered during Cycle 12 with RXTE, to provide an ephemeris for GLAST. These timing observations will be interesting for measuring braking indexes and studying glitching behavior in energetic pulsars.

18

RXTE Timing of New Energetic Pulsars for Glast  

NASA Astrophysics Data System (ADS)

GLAST is expected to detect many new gamma-ray pulsars, and hopefully solve problem of unidentified gamma-ray sources. However, detecting pulsars requires phase-coherent monitoring to provide a pulse ephemeris with which to fold the gamma-ray data. This is because of the paucity of gamma-ray photons, which demands ~year long integration times, coupled with the timing noise and glitches seen in the best GLAST targets. For radio-quiet pulsars, regular RXTE monitoring is the only practical option for coherent timing. We propose to time any radio- quiet energetic young X-ray pulsar discovered during Cycle 12 with RXTE, to provide an ephemeris for GLAST. These timing observations will be interesting for measuring braking indexes and studying glitching behavior in energetic pulsars.

Kaspi, Victoria

19

RXTE Observations of LMC X-1 and LMC X-3  

NASA Technical Reports Server (NTRS)

Of all known persistent stellar-mass black hole candidates, only LMC X-1 and LMC X-3 consistently show spectra that are dominated by a soft, thermal component. We present results from long (170 ksec) Rossi X-ray Timing Explorer (RXTE) observations of LMC X-1 and LMC X-3 made in 1996 December. The spectra can be described by a multicolor disk blackbody plus an additional high-energy power-law. Even though the spectra are very soft (Gamma approximately 2.5), RXTE detected a significant signal from LMC X-3 up to energies of 50 keV, the hardest energy at which the object was ever detected. Focusing on LMC X-3, we present results from the first year of an ongoing monitoring campaign with RXTE which started in 1997 January. We show that the appearance of the object changes considerably over its approximately 200d long cycle. This variability can either be explained by periodic changes in the mass transfer rate or by a precessing accretion disk analogous to Her X-1.

Wilms, J.; Nowak, M. A.; Dove, J. B.; Pottschmidt, K.; Heindl, W. A.; Begelman, M. C.; Staubert, R.

1998-01-01

20

RXTE Observations of LMC X-1 and LMC X-3  

NASA Technical Reports Server (NTRS)

Of all known persistent stellar-mass black hole candidates, only LMC X-1 and LMC X-3 consistently show spectra that are dominated by a soft, thermal component. We present results from long (170 ksec) Rossi X-ray Timing Explorer (RXTE) observations of LMC X-1 and LMC X-3 made in 1996 December. The spectra can be described by a multicolor disk blackbody plus an additional high-energy power-law. Even though the spectra are very soft (Gamma approximately 2.5), RXTE detected a significant signal from LMC X-3 up to energies of 50 keV, the hardest energy at which the object was ever detected. Focusing on LMC X-3 , we present results from the first year of an ongoing monitoring campaign with RXTE which started in 1997 January. We show that the appearance of the object changes considerably over its approximately 200 d long cycle. This variability can either be explained by periodic changes in the mass transfer rate or by a precessing accretion disk analogous to Her X-1.

Wilms, J.; Nowak, M. A.; Dove, J. B.; Pottschmidt, K.; Heindl, W. A.; Begelman, M. C.; Staubert, R.

1999-01-01

21

RXTE Observation of Cygnus X-1. Report 2; TIming Analysis  

NASA Technical Reports Server (NTRS)

We present timing analysis for a Rossi X-ray Timing Explorer (RXTE) observation of Cygnus X-1 in its hard/low state. This was the first RXTE observation of Cyg X-1 taken after it transited back to this state from its soft/high state. RXTE's large effective area, superior timing capabilities, and ability to obtain long, uninterrupted observations have allowed us to obtain measurements of the power spectral density (PSD), coherence function, and Fourier time lags to a decade lower in frequency and half a decade higher in frequency than typically was achieved with previous instruments. Notable aspects of our observations include a weak 0.005 Hz feature in the PSD coincident with a coherence recovery; a 'hardening' of the high-frequency PSD with increasing energy; a broad frequency range measurement of the coherence function, revealing rollovers from unity coherence at both low and high frequency; and an accurate determination of the Fourier time lags over two and a half decades in frequency. As has been noted in previous similar observations, the time delay is approximately proportional to f(exp -0.7), and at a fixed Fourier frequency the time delay of the hard X-rays compared to the softest energy channel tends to increase logarithmically with energy. Curiously, the 0.01-0.2 Hz coherence between the highest and lowest energy bands is actually slightly greater than the coherence between the second highest and lowest energy bands. We carefully describe all of the analysis techniques used in this paper, and we make comparisons of the data to general theoretical expectations. In a companion paper, we make specific comparisons to a Compton corona model that we have successfully used to describe the energy spectral data from this observation.

Nowak, Michael A.; Vaughan, Brian A.; Wilms, Joern; Dove, James B.; Begelman, Mitchell C.

1998-01-01

22

RXTE monitoring of the intermediate polar TX Col  

NASA Astrophysics Data System (ADS)

I present a preliminary analysis of ongoing monthly X-ray observations of TX Col with RXTE. The lightcurves confirm that the relative strength of spin and beat modulations is highly variable in this system, and show that the timescale of variation is shorter than one month. Changes in these modulations are thought to represent a change in accretion geometry, possibly governed by a varying accretion rate. I find some evidence that the ratio of spin to beat amplitudes is correlated with the mean count rate.

Wheatley, Peter J.

23

Analysis of RXTE data on Clusters of Galaxies  

NASA Technical Reports Server (NTRS)

This grant provided support for the reduction, analysis and interpretation of of hard X-ray (HXR, for short) observations of the cluster of galaxies RXJO658--5557 scheduled for the week of August 23, 2002 under the RXTE Cycle 7 program (PI Vahe Petrosian, Obs. ID 70165). The goal of the observation was to search for and characterize the shape of the HXR component beyond the well established thermal soft X-ray (SXR) component. Such hard components have been detected in several nearby clusters. distant cluster would provide information on the characteristics of this radiation at a different epoch in the evolution of the imiverse and shed light on its origin. We (Petrosian, 2001) have argued that thermal bremsstrahlung, as proposed earlier, cannot be the mechanism for the production of the HXRs and that the most likely mechanism is Compton upscattering of the cosmic microwave radiation by relativistic electrons which are known to be present in the clusters and be responsible for the observed radio emission. Based on this picture we estimated that this cluster, in spite of its relatively large distance, will have HXR signal comparable to the other nearby ones. The planned observation of a relatively The proposed RXTE observations were carried out and the data have been analyzed. We detect a hard X-ray tail in the spectrum of this cluster with a flux very nearly equal to our predicted value. This has strengthen the case for the Compton scattering model. We intend the data obtained via this observation to be a part of a larger data set. We have identified other clusters of galaxies (in archival RXTE and other instrument data sets) with sufficiently high quality data where we can search for and measure (or at least put meaningful limits) on the strength of the hard component. With these studies we expect to clarify the mechanism for acceleration of particles in the intercluster medium and provide guidance for future observations of this intriguing phenomenon by instrument on GLAST. The details of the nonthermal particle population has important implications for the theories of cluster formation, mergers and evolution. The results of this work were first presented at the High Energy Division meeting of the American astronomical Society at Mt. Tremblene, Canada (Petrosian et al. 2003). and in an invited review talk at the General Assembly of the International Astronomical Union at Sydney, Australia (Petrosian, 2003). A paper describe the observations, the data analysis and its implication is being prepared for publication in the Astrophysical Journal.

Petrosian, Vahe

2004-01-01

24

RXTE Observation of PSR B1951+32  

E-print Network

We report results of RXTE observations of PSR B1951+32 using the PCA instrument for 19k seconds during 1996 March 24th. We applied the contemporaneous radio ephemeris and various statistical tests to search for evidence of pulsation. These analyses yield intriguing yet inconclusive evidence for the presence of the pulsation in the time series: confidence level for the presence of pulsation is 94.5% in the 2.0-4.8 keV band and 97.6% in the 4.8-6.3 keV band based on the H-test. Under the premise of non-detection of pulsation, we derive estimated 2-sigma upper limits for the pulsed flux to be $3.3\\times 10^{-6} cm^{-2} s^{-1} keV^{-1}$ in the 2.0-4.8 keV band, $2.7\\times 10^{-6} cm^{-2} s^{-1} keV^{-1}$ in the 4.8-8.5 keV band, and $2.0\\times 10^{-6} cm^{-2} s^{-1} keV^{-1}$ in the 8.5-13.0 keV band. These upper limits are consistent with the trend of spectral turn-over from high-energy gamma-ray emission as suggested by the OSSE upper limit. Such turn-over strongly suggests the outer magnetosphere as the emission site for pulsed gamma-rays. These RXTE upper limits for X-ray pulsation are, on the other hand, not consistent with the extrapolation of reported power-law spectra from the point source observed by ROSAT in the 0.1-2.4 keV band, assuming a constant pulse fraction: The pulsed soft X-ray emission detected by ROSAT must follow a much softer spectrum than that of the overall point source.

Hsiang-Kuang Chang; Cheng Ho

1997-02-02

25

A bright thermonuclear X-ray burst simultaneously observed with Chandra and RXTE  

E-print Network

The prototypical accretion-powered millisecond pulsar SAX J1808.4?3658 was observed simultaneously with Chandra-LETGS and RXTE-PCA near the peak of a transient outburst in November 2011. A single thermonuclear (type-I) ...

in ’t Zand, J. J. M.

26

Science Fair Competition Generates Excitement and Promotes Creative Thinking in Japan  

ERIC Educational Resources Information Center

Educators in the U.S. and Japan have developed an international program to promote creative thinking in science. Their program includes a science fair component. This paper (which has been presented in both the U.S. and Japan) discusses creativity and describes a science fair activity, that the authors recently carried out in Japan. The special…

Barry, Dana M.; Kanematsu, Hideyuki

2006-01-01

27

Advances in the RXTE Proportional Counter Array Calibration: Nearing the Statistical Limit  

NASA Technical Reports Server (NTRS)

During its 16 years of service Rossi X-ray Timing Explorer (RXTE) mission has provided an extensive archive of data, which will serve as a primary source of high cadence observation of variable X-ray sources for fast timing studies. It is, therefore, very important to have the most reliable calibration of RXTE instruments. The Proportional Counter Array (PCA) is the primary instrument on-board RXTE which provides data in 2-50 keY with higher than millisecond time resolution in up to 256 energy channels. In 2009 RXTE team revised the response residual minimization method used to derive the parameters of the PCA physical model. The procedure is now based on the residual minimization between the model spectrum for Crab nebula emission and a calibration data set consisting of a number of spectra from the Crab and the on-board Am241 calibration source, uniformly covering a whole RXTE span. The new method led to a much more effective model convergence and allowed for better understanding of the behavior of the PCA energy-to-channel relationship. It greatly improved the response matrix performance. We describe the new version of the RXTE/PCA response generator PCARMF vll.7 along with the corresponding energy-to-channel conversion table (version e05v04) and their difference from the previous releases of PCA calibration. The new PCA response adequately represents the spectrum of the calibration sources and successfully predicts the energy of the narrow iron emission line in Cas-A throughout the RXTE mission.

Shaposhnikov, Nikolai; Jahoda, Keith; Markwardt, Craig; Swank, Jean; Strohmayer, Tod

2012-01-01

28

The Excitement and Wonder of Teaching Science: What Pre-Service Teachers Learn from Facilitating Family Science Night Centers  

ERIC Educational Resources Information Center

In this study, pre-service teachers facilitated stations at a family science night as a context to learn to identify, assess, and use children's science ideas. Assessment is already difficult in K-12 classrooms. Assessing learning in informal learning environments adds the complication that participation is largely voluntary. As such, controlling…

Harlow, Danielle B.

2012-01-01

29

RXTE, ROSAT, EUVE, IUE, and Optical Observations through the 45 Day Supercycle of V1159 Orionis  

Microsoft Academic Search

A complete 45 day supercycle of the cataclysmic variable V1159 Ori comprising a superoutburst and eight normal outbursts was observed. Coverage included ground-based optical observations as well as observations with RXTE for 38 days, ROSAT for 34 days, IUE for 27 days, and Extreme Ultraviolet Explorer (EUVE) for 10 days. The resulting light curves reveal that the optical and UV

Paula Szkody; A. Linnell; Kent Honeycutt; Jeff Robertson; Andrew Silber; D. W. Hoard; L. Pastwick; V. Desai; Ivan Hubeny; John Cannizzo; William Liller; Ronald Zissell; Gary Walker

1999-01-01

30

Long-Term Monitoring of PSR B0540-69 with RXTE  

NASA Technical Reports Server (NTRS)

RXTE has monitored PSR B0540-69, the young, Crab-like pulsar in the LMC, since early January 1999 and maintained a phase-connected timing solution. We report on a search for glitches in phase or frequency, changes in the braking index, and a determination of the pulsar position.

Marshall, Francis

2012-01-01

31

International Journal of Systems Science, 2000, volume 31, number 4, pages 519 527 Multi machine power system excitation control design via theories  

E-print Network

International Journal of Systems Science, 2000, volume 31, number 4, pages 519± 527 Multi machine power system excitation control design via theories of feedback linearization control and nonlinear robust control DEQIANG GAN{, ZHIHUA QU{ and HONGZHI CAI{ The dynamics of a large-scale power system

Qu, Zhihua

32

Sharing the excitement of deep ocean research The UK has long prided itself on its achievements in science, engineering and technology. They contribute  

E-print Network

Sharing the excitement of deep ocean research The UK has long prided itself on its achievements build a legacy of inspiration and curiosity in the UK. Researchers in Ocean and Earth Science at universities around the world to further our knowledge. One major research area is the deep oceans where much

Anderson, Jim

33

RXTE, Chandra, and XMM Spectroscopy of the Fe-K Lines and Compton Reflection in Type 1 AGN  

NASA Technical Reports Server (NTRS)

This award pertains to an RXTE observation of the Seyfert 1 galaxy Akn 120. The purpose of the observation was to measure the Fe-K emission line and the Compton reflection continuum with RXTE, simultaneously with Chandra and XMM. Such measurements can severely constrain accretion disk models of the central engine since the Fe-K line emission and Compton reflection are intimately related in terms of the physics of X-ray reprocessing in optically-thick matter. Akn 120 was selected for this study because it is amongst the brightest AGN in its class and has a particularly strong and apparently broad Fe-K emission line. The results could then also be used to lay the ground work for even higher resolution studies with Astro-E2. Unfortunately, the Chandra observation was not performed but a contemporaneous XMM observation was performed by another group of researchers. Those data recently became public and can be compared with the RXTE data. In addition, non-contemporaneous observations with other missions do still provide additional important constraints (for example any non-varying line or continuum emission components can be established and used to reject or preserve various model scenarios). We analyzed the RXTE data and found a strong Fe-K emission line (resolved even with the poor resolution of RXTE), and a strong Compton-reflection continuum (see Fig. l(a)). We found that the results of archival ASCA data on Akn 120 had not been published in the literature so we analyzed the ASCA data too, in order to compare with the new RXTE data. Fig. l(b) shows that the ASCA data also reveal a strong, broad FeK emission line (but the data are not sensitive to the Compton-reflection continuum). We compared our spectral fitting results for the RXTE and ASCA data with the results from XMM and from previous RXTE observations.

Yaqoob, Tahir

2004-01-01

34

Swift, INTEGRAL, RXTE, and Spitzer Reveal IGR J16283-4838  

NASA Technical Reports Server (NTRS)

We present the first combined study of the recently discovered source IGR J16283-4838 with Swift, INTEGRAL, and RXTE. The source, discovered by INTEGRAL on April 7, 2005, shows a highly absorbed (variable N(sub H) = 0.4-1.7 x 10(exp 23) /sq cm) and flat (Gamma approx. 1) spectrum in the Swift/XRT and RXTE/PCA data. No optical counterpart is detectable (V > 20 mag), but a possible infrared counterpart within the Swift/XRT error radius is detected in the 2MASS and Spitzer/GLIMPSE survey. The observations suggest that IGR J16283-4838 is a high mass X-ray binary containing a neutron star embedded in Compton thick material. This makes IGR J16283-4838 a member of the class of highly absorbed HMXBs, discovered by INTEGRAL.

Beckmann, V.; Gehrels, N.; Markwardt, C.; Barthelmy S.; Soldi, S.; Paizis, A.; Mowlavi, N.; Kennca, J. A.; Burrows, D. N.; Chester, M.

2005-01-01

35

Observation of Nonthermal Emission from the Supernova Remnant IC443 with RXTE  

NASA Technical Reports Server (NTRS)

In this paper we present analysis of X-ray spectra from the supernova remnant IC443 obtained using the PCA on RXTE. The spectra in the 3 - 20 keV band are well fit by a two-component model consisting of thermal and nonthermal components. We compare these results with recent results of other X-ray missions and discuss the need for a cut-off in the nonthermal spectrum. Recent Chandra and XMM-Newton observations suggest that much of the nonthermal emission from IC443 can be attributed to a pulsar wind nebula. We present the results of our search for periodic emission in the RXTE PCA data. We then discuss the origin o f the nonthermal component and its possible association with the unidentified EGRET source.

Sturner, S. J.; Keohane, J. W.; Reimer, O.

2002-01-01

36

ASCA, RXTE, EUVE, and Optical Observations of the High Magnetic Field Cataclysmic Variable AR Ursae Majoris  

Microsoft Academic Search

The highest field polar AR UMa was observed with ASCA during a low state, and with simultaneous EUVE, RXTE, and ground-based optical photometry during a high state. The marginal detection at the low state places a limit on the hard X-ray emission, which is a factor of 5 below the high-state flux limit. The high-state EUV light curves are highly

Paula Szkody; Stéphane Vennes; Gary D. Schmidt; R. Mark Wagner; Robert Fried; Allen W. Shafter; Erik Fierce

1999-01-01

37

Millisecond dips in the RXTE/PCA light curve of Sco X-1 and TNO occultation  

E-print Network

Millisecond dips in the RXTE/PCA light curve of Sco X-1 were reported recently (Chang et al. 2006), which were interpreted as the occultation of X-rays from Sco X-1 caused by Trans-Neptunian Objects (TNO) of hundred-meter size. Inconclusive signatures of possible instrumental effects in many of these dip events related to high-energy cosmic rays were later found (Jones et al. 2006) and the TNO interpretation became shaky. Here we report more detailed analysis aiming at distinguishing true occultation events from those related to cosmic rays. Based on some indicative criteria derived from housekeeping data and two-channel spectral information, we suggest that about 10% of the dips are probable events of occultation. The total number of TNOs of size from 60 m to 100 m is estiamted to be about 10^{15} accordingly. Limited by the coarser time resolution of standard data modes of RXTE/PCA, however, definite results cannot be obtained. Adequately configured observations with RXTE or other new instruments in the future are very much desired.

Hsiang-Kuang Chang; Jau-Shian Liang; Chih-Yuan Liu; Sun-Kun King

2007-01-30

38

Timing Studies on RXTE Observations of SAX J2103.5+4545  

E-print Network

SAX J2103.5+4545 has been continuously monitored for $\\sim $ 900 days by Rossi X-ray Timing Explorer (RXTE) since its outburst in July 2002. Using these observations and previous archival RXTE observations of SAX J2103.5+4545, we refined the binary orbital parameters and find the new orbital period as P= (12.66536 $\\pm $ 0.00088) days and the eccentricity as 0.4055$\\pm$ 0.0032. With these new orbital parameters, we constructed the pulse frequency and pulse frequency derivative histories of the pulsar and confirmed the correlation between X-ray flux and pulse frequency derivative presented by Baykal, Stark and Swank (2002). We constructed the power spectra for the fluctuations of pulse frequency derivatives and found that the power law index of the noise spectra is 2.13 $\\pm$ 0.6. The power law index is consistent with random walk in pulse frequency derivative and is the steepest among the HMXRBs. X-ray spectra analysis confirmed the inverse correlation trend between power-law index and X-ray flux found by Baykal, Stark and Swank (2002).

A. Baykal; S. C. Inam; M. J. Stark; C. M. Heffner; A. E. Erkoca; J. H. Swank

2006-08-30

39

RXTE and Swift observations of SWIFT J1729.9-3437  

NASA Astrophysics Data System (ADS)

We analyse Rossi X-ray Timing Explorer (RXTE) and Swift observations of SWIFT J1729.9-3437 after its outburst from 2010 July 20 to 2010 August 12. We calculate a spin frequency and spin frequency derivative of 1.8734(8) × 10-3 Hz and 6.42(6) × 10-12 Hz s-1, respectively from the quadratic fit of the pulse arrival times. The quadratic fit residuals fit well to a circular orbital model with a period of 15.3(2) d and a mass function of about 1.3 M?, but they can also be explained by a torque noise strength of 6.8 × 10-18 Hz s-2. Pulse profiles switch from double peaked to single peaked as the source flux continues to decrease. We find that the pulse shape generally shows no strong energy dependence. The hardness ratios reveal that the source becomes softer with decreasing flux. We construct a single spectrum from all the available RXTE and Swift observations. We find that adding an Fe line complex feature around 6.51 keV slightly improves the spectral fit. We also find that Fe line flux correlates with X-ray flux which might indicate the origin of the Fe emission as the source itself rather than the Galactic ridge.

?ahiner, ?.; ?nam, S. Ç.; Serim, M. M.; Baykal, A.

2013-10-01

40

MULTIWAVELENGTH OBSERVATIONS OF LS I +61{sup 0} 303 WITH VERITAS, SWIFT, AND RXTE  

SciTech Connect

We present results from a long-term monitoring campaign on the TeV binary LSI +61{sup 0} 303 with VERITAS at energies above 500 GeV, and in the 2-10 keV hard X-ray bands with RXTE and Swift, sampling nine 26.5 day orbital cycles between 2006 September and 2008 February. The binary was observed by VERITAS to be variable, with all integrated observations resulting in a detection at the 8.8{sigma} (2006/2007) and 7.3{sigma} (2007/2008) significance level for emission above 500 GeV. The source was detected during active periods with flux values ranging from 5% to 20% of the Crab Nebula, varying over the course of a single orbital cycle. Additionally, the observations conducted in the 2007-2008 observing season show marginal evidence (at the 3.6{sigma} significance level) for TeV emission outside the apastron passage of the compact object around the Be star. Contemporaneous hard X-ray observations with RXTE and Swift show large variability with flux values typically varying between 0.5 and 3.0 x10{sup -11} erg cm{sup -2} s{sup -1} over a single orbital cycle. The contemporaneous X-ray and TeV data are examined and it is shown that the TeV sampling is not dense enough to detect a correlation between the two bands.

Acciari, V. A. [Department of Life and Physical Sciences, Galway-Mayo Institute of Technology, Dublin Road, Galway (Ireland); Aliu, E. [Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware, Newark, DE 19716 (United States); Arlen, T.; Chow, Y. C. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Bautista, M.; Cogan, P. [Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada); Beilicke, M.; Bugaev, V. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Benbow, W. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Boettcher, M. [Astrophysical Institute, Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States); Bradbury, S. M.; Daniel, M. [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Butt, Y.; Butt, Y. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Byrum, K. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Cannon, A. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Cesarini, A. [School of Physics, National University of Ireland, Galway (Ireland); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Colin, P. [Physics Department, University of Utah, Salt Lake City, UT 84112 (United States); Cui, W. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States)], E-mail: awsmith@hep.anl.gov (and others)

2009-08-01

41

Low Luminosity States of the Black Hole Candidate GX 339-4. 1; ASCA and Simultaneous Radio/RXTE Observations  

NASA Technical Reports Server (NTRS)

We discuss a series of observations of the black hole candidate GX 339-4 in low luminosity, spectrally hard states. We present spectral analysis of three separate archival Advanced Satellite for Cosmology and Astrophysics (ASCA) data sets and eight separate Rossi X-ray Timing Explorer (RXTE) data sets. Three of the RXTE observations were strictly simultaneous with 843 Mega Hertz and 8.3-9.1 Giga Hertz radio observations. All of these observations have (3-9 keV) flux approximately less than 10(exp-9) ergs s(exp-1) CM(exp -2). The ASCA data show evidence for an approximately 6.4 keV Fe line with equivalent width approximately 40 eV, as well as evidence for a soft excess that is well-modeled by a power law plus a multicolor blackbody spectrum with peak temperature approximately equals 150-200 eV. The RXTE data sets also show evidence of an Fe line with equivalent widths approximately equal to 20-1OO eV. Reflection models show a hardening of the RXTE spectra with decreasing X-ray flux; however, these models do not exhibit evidence of a correlation between the photon index of the incident power law flux and the solid angle subtended by the reflector. 'Sphere+disk' Comptonization models and Advection Dominated Accretion Flow (ADAF) models also provide reasonable descriptions of the RXTE data. The former models yield coronal temperatures in the range 20-50 keV and optical depths of r approximately equal to 3. The model fits to the X-ray data, however, do not simultaneously explain the observed radio properties. The most likely source of the radio flux is synchrotron emission from an extended outflow of extent greater than O(10 (exp7) GM/c2).

Wilms, Joern; Nowak, Michael A.; Dove, James B.; Fender, Robert P.; DiMatteo, Tiziana

1998-01-01

42

Peculiar Outburst of A 0535+26 Observed with INTEGRAL, RXTE and Suzaku  

NASA Technical Reports Server (NTRS)

A normal outburst of the Be/X-ray binary system A0535+26 has taken place in August 2009. It is the fourth in a series of normal outbursts that have occurred around the periastron passage of the source. but is unusual by starting at an earlier orbital phase and by presenting a peculiar double-peaked light curve. A first "flare" (lasting about 9 days from M.ID 55043 on) reached a flux of 440 mCrab. The flux then decreased to less than 220 mCrab. and increased again reaching 440 mCrab around the periastron at MJD 55057. Target of Opportunity observations have been performed with INTEGRAL. RXTE and Suzaku. First results of these observations are presented. with special emphasis on the cyclotron lines present in the X-ray spectrum of the source. as well as in the pulse period and energy dependent pulse profiles of the source

Caballero, I.; Pottschmidt, K.; Barragan, L.; Ferrigno, C.; Kretschmar, P.; Suchy, S.; Wilms, J.; Santangelo, A.; Kreykenbohm, I.; Rothschild, R.; Klochkov, D.; Staubert, R.; Finger, M. H.; Camero-Arranz, A.; Makishima, K.; Enoto, T.

2009-01-01

43

Neutron Stars and Black Holes Seen with the Rossi X-Ray Timing Explorer (RXTE)  

NASA Technical Reports Server (NTRS)

Astrophysical X-rays bring information about location, energy, time, and polarization. X-rays from compact objects were seen in the first explorations to vary in time. Eclipses and pulsations have simple explanations that identified the importance of X-ray binaries and magnetic neutron stars in the first decade of X-ray astronomy. The dynamics of accretion onto stellar and supermassive black holes and onto neutron stars with relatively low magnetic fields shows up as more complex variations, quasi-periodic oscillations, noise with characteristic frequency spectra, broad-band changes in the energy spectra. To study these variations, RXTE instruments needed to have large area and operational flexibility to find transient activity and observe when it was present. Proportional counters and Phoswich scintillators provided it in a modest mission that has made textbook level contributions to understanding of compact objects. The first seen, and the brightest known, X-ray binary, Sco X-1 is one of a class of neutron stars with low mass companions. Before RXTE, none of these had been seen to show pulsations, though they were hypothesized to be the precursors of radio pulsars with millisecond periods and low magnetic fields. RXTE's large area led to identifying coherent millisecond pulsars in a subset which are relatively faint transients. It also led to identifying short episodes of pulsation during thermonuclear bursts, in sources where a steady signal is not seen. The X-ray stage verifies the evolution that produces millisecond radio pulsars.Masses and radii of neutron stars are being determined by various techniques, constraining the equation of state of matter at nuclear densities. Accretion should lead to a range of neutron star masses. An early stage of superstrong magnetic field neutron stars is now known to produce X-ray and gamma-ray bursts in crust quakes and magnetic field reconnection releases of energy. Soft Gamma Repeaters, Anomolous X-ray Pulsars, and high magnetic field rotation-powered pulsars are all now called magnetars, because they have pulse periods indicating they are slowing down as they would with magnetic dipole radiation for a surface field above 5x1013 gauss. The accretion disk has been connected to the launching of radio jets from black holes, and even from neutron stars. Estimates of the angular momenta of black holes are being made from different approaches, modelling a high frequency oscillation that may be related to how close the inner part of the accretion disk is to the black hole, modelling the continua spectra of the X-ray emission, and modeling the emission of red-shifted iron that may be emitted from the accretion disk. These investigations require early discovery of the black hole transient with the All Sky Monitor on RXTE or other monitoring information, frequent extended observations, and coordinated observations with missions that give higher energy resolution, or radio and infrared information.

Swank, Jean

2008-01-01

44

A DOUBLE-PEAKED OUTBURST OF A 0535+26 OBSERVED WITH INTEGRAL, RXTE, AND SUZAKU  

SciTech Connect

The Be/X-ray binary A 0535+26 showed a normal (type I) outburst in 2009 August. It is the fourth in a series of normal outbursts associated with the periastron, but is unusual because it presented a double-peaked light curve. The two peaks reached a flux of {approx}450 mCrab in the 15-50 keV range. We present results of the timing and spectral analysis of INTEGRAL, RXTE, and Suzaku observations of the outburst. The energy-dependent pulse profiles and their evolution during the outburst are studied. No significant differences with respect to other normal outbursts are observed. The centroid energy of the fundamental cyclotron line shows no significant variation during the outburst. A spectral hardening with increasing luminosity is observed. We conclude that the source is accreting in the sub-critical regime. We discuss possible explanations for the double-peaked outburst.

Caballero, I. [Laboratoire AIM, CEA/IRFU, CNRS/INSU, Universite Paris Diderot, CEA DSM/IRFU/SAp, F-91191 Gif-sur-Yvette (France); Pottschmidt, K.; Marcu, D. M. [Center for Space Science and Technology, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Barragan, L.; Wilms, J.; Kreykenbohm, I. [Dr. Karl Remeis-Sternwarte and ECAP, FAU Erlangen-Nuremberg, Sternwartstr. 7, D-96049 Bamberg (Germany); Ferrigno, C. [ISDC Data Centre for Astrophysics, University of Geneva, Chemin d'Ecogia 16, CH-1290 Versoix (Switzerland); Klochkov, D.; Suchy, S.; Santangelo, A.; Staubert, R. [Institut fuer Astronomie und Astrophysik, Sand 1, D-72076 Tuebingen (Germany); Zurita Heras, J. A. [Francois Arago Centre, APC (UMR 7164 Universite Paris Diderot, CNRS/IN2P3, CEA/DSM, Observatoire de Paris), 13 rue Watt, F-75205 Paris Cedex 13 (France); Kretschmar, P. [European Space Astronomy Centre (ESA/ESAC), Science Operations Department, Villanueva de la Canada, E-28080 Madrid (Spain); Fuerst, F. [Space Radiation Lab, California Institute of Technology, MC 290-17 Cahill, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Rothschild, R. [Center for Astrophysics and Space Science, UCSD, La Jolla, CA 92093 (United States); Finger, M. H. [National Space Science and Technology Center, 320 Sparkman Drive NW, Huntsville, AL 35805 (United States); Camero-Arranz, A. [Institut de Ciencies de l'Espai (IEEC-CSIC), Campus UAB, Fac. de Ciencies, Torre C5, parell, 2a planta, E-08193 Barcelona (Spain); Makishima, K. [Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Enoto, T. [Cosmic Radiation Laboratory, RIKEN, 2-1, Hirosawa, Wako City, Saitama 351-0198 (Japan); Iwakiri, W., E-mail: isabel.caballero@cea.fr [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570 (Japan); and others

2013-02-20

45

The Broadband Continuum Spectrum of Magnetar Bursts from Swift and RXTE  

NASA Astrophysics Data System (ADS)

We studied a large number of SGR bursts with Swift and RXTE to determine the best fit continuum model in the broad range of 2-350 keV. Using 10 trial models, we find acceptable fits with single component Optically thin thermal Bremsstarahlung, Cutoff Power-law, and simple Power-law models that rule out the need for a second component. We present the global spectral properties of the bursts and investigation spectral-temporal correlations. (*) This contribution presents results from students projects carried out during the 8th COSPAR Capacity Building Workshop on Space Astrophysics with NASA & ESA Missions: Swift, Chandra & XMM Newton (Jan. 20-Feb. 2, 2008; Alexandria, Egypt; http://cais.cu.edu.eg/astro)

Ibrahim, Alaa

46

Using Remote Sensing Technology, Web Casts, and Participation in a Valuable Research Project to Jazz Teachers and Excite Students About Science  

NASA Astrophysics Data System (ADS)

Scientific education of primary and secondary school children has become a topic of concern in Ohio and throughout the United States. So with that in mind, how do you get students excited about learning science? One route is to inform and jazz teachers about current technology! The University of Toledo has hosted three one-week, NASA and OhioView sponsored professional development institutes entitled, Observing Earth from Space, for teachers from grades K-12 during July 2000, 2001, and 2002. Sixty-seven teachers from the Upper Midwest and Kansas with Earth Science, Social Studies, and Physics backgrounds attended. Each participant acquired new ideas, plenty of educational materials, and posters of satellite imagery. The teachers received basic training in remote sensing, global positioning systems, digital elevation models, and weather observing techniques and learned about useful remote sensing applications. This instruction was conducted through: 1) presentations given by research scientists, 2) integration of the learned content into authentic, hands-on lesson plans, and 3) participation in a learning adventure, where their students collected real-time earth science data at their respective schools while university research scientists gathered corresponding satellite imagery. The students observations were submitted via a simple Web interface: www.remotesensing.utoledo.edu. One of the very exciting platforms used to communicate with the teachers and students throughout the school year were live Web Casts sponsored by NASA Glenn Research Center. The students data have successfully assisted in the validation of cloud/snow remote sensing algorithms, and next year the students observations will include various surface temperature readings. The participation in a cutting-edge technology workshop and in an important global climate change research project, applicable in the classroom, has added another worthwhile dimension to the learning process and career awareness for both the teachers and their students.

Benko, T. M.; Czajkowski, K. P.; Struble, J.; Zhao, L.

2002-12-01

47

Map, Excite, Jump, and Measure: An Outreach Activity That Utilizes Seismology to Engage Students in Technology, Science, Engineering, and Mathematics  

NASA Astrophysics Data System (ADS)

We designed and will present a lesson plan to teach students STEM concepts through seismology. The plan addresses new generation science standards in the Framework for K-12 Science Education as well AAAS Benchmarks for Science Literacy. The plan can be executed at a facility with a seismometer in a research facility or university, on a field trip, but it can also be used in a school setting with a school seismometer. Within the lesson plan, the students first use technology to obtain earthquake location data and map them. Next, the students learn about the science of earthquakes, which is followed by an engineering activity in which the students design a hypothetical seismometer and interact with the actual seismometer and live data display. Lastly the students use mathematics to locate an earthquake through trilateration. The lesson plan has been fine-tuned through implementation with over 150 students from grades 3-12 from the Chicago area.

van der Lee, S.; Tekverk, K.; Rooney, K.; Boxerman, J.

2013-12-01

48

The Crab Pulsar Observed by RXTE: Monitoring the X-Ray to Radio Delay for 16 Years  

NASA Technical Reports Server (NTRS)

In 2004 we published the results of monitoring the Crab Pulsar by RXTE. At that time we determined that the primary pulse of the pulsar at X-ray energies precedes its radio counterpart by about 0.01 period in phase or approximately 330 micro seconds. However, we could not establish unambiguously whether the delay is in phase or due to a difference in pathlength. At this time we have twice the time baseline we had in 2004 and we present the same analysis, but now over a period of 16 years, which will represent almost the full mission and the best that will be available from RXTE. The full dataset shows that the phase delay has been decreasing faster than the pulse frequency over the 16 year baseline and that there are variations in the delay on a variety of timescales.

Rots, Arnold; Jahoda, Keith

2012-01-01

49

Excite Travel  

NSDL National Science Digital Library

Excite Travel is one of the most comprehensive international guides to communities around the world. Excite Travel provides easy and timely access to information on travel, entertainment, and local business, plus government and community services for all regions of the world.

50

RXTE timing analysis of the anomalous X-ray pulsar 1E 2259+586  

NASA Astrophysics Data System (ADS)

We present a pulse-timing analysis of Rossi X-ray Timing Explorer (RXTE) observations of the anomalous X-ray pulsar 1E 2259+586 from its 2002 outburst to 2010 October. We have the following objectives: to extend the work on the recovery stage after the 2002 glitch; to investigate the variations caused by the second glitch that occurred in 2007; to look for other unusual events, if any, that arise in the regular spin-down trend of the source. We find that the fractional change in the spin frequency derivative after the 2002 glitch is not stable as it decreased by an order of magnitude, from -2.2 × 10-2 to -1.278(3) × 10-3, in about 2.5 yr. Using a pulse-timing analysis, we discover two small frequency shifts with fractional changes ??/?= 3.08(32) × 10-8 and ??/?=-1.39(11) × 10-8. While the first of these shifts is not found to have a fractional frequency derivative change, the second has ?. We interpret these frequency changes as positive and negative microglitches, similar to those seen in radio pulsars.

Içdem, B.; Baykal, A.; Inam, S. Ç.

2012-02-01

51

Orbital Phase Spectroscopy of GX 301--2 with RXTE-PCA  

E-print Network

We have investigated the orbital phase dependence of the X-ray spectrum of the High Mass X-ray Binary pulsar GX 301--2. Here we present the results from a spectral analysis of two sets of observations of GX 301--2 with the Rossi X-ray Timing Explorer (RXTE). Of particular interest are the variations of the absorption column density and the iron line flux along with other parameters of the spectral model with the orbital phase. We found that the X-ray spectrum can almost always be fitted with a partial covering absorption model. We have detected enhanced absorption near the periastron. However, the column density variation with orbital phase is not smooth, as is expected in a smooth stellar wind model. We discuss the results of the column density variation in the light of the two proposed models for GX 301-2, an equatorial disk emanating from the companion star Wray 977 and a gas stream following the neutron star. We also found that the iron K_alpha and K_beta line fluxes have peaks near the periastron and are well correlated with the continuum hard X-ray flux. The line equivalent width shows an interesting pattern with the column density, reasonably constant for low values of the column density and increasing rapidly beyond a certain value.

U. Mukherjee; B. Paul

2004-09-02

52

RXTE-PCA Observations of XMMU J054134.7-682550  

E-print Network

We analyzed RXTE-PCA observations of a recent outburst of the X-ray pulsar XMMU J054134.7$-$682550. We calculated the pulse frequency history of the source. We found no sign of a binary companion. The source spins up when the X-ray flux is higher, with a correlation between the spin-up rate and X-ray flux, which may be interpreted as a sign of an accretion disk. On the other hand, the source was found to have an almost constant spin frequency when the X-ray flux is lower without any clear sign of a spin-down episode. The decrease in pulsed fraction with decreasing X-ray flux was intrepreted as a sign of accretion geometry change, but we did not find any evidence of a transition from accretor to propeller regimes. The source was found to have variable pulse profiles. Two peaks in pulse profiles were usually observed. We studied the X-ray spectral evolution of the source throughout the observation. Pulse phase resolved analysis does not provide any further evidence for a cyclotron line, but may suggest a slight variation of intensity and width of the 6.4 keV iron line with phase.

S. C. Inam; L. J. Townsend; V. A. McBride; A. Baykal; M. J. Coe; R. H. D. Corbet

2008-10-06

53

Monitoring the Black Hole Binary GRS 1758-258 with INTEGRAL and RXTE  

NASA Technical Reports Server (NTRS)

The microquasar GRS 1758-258 is one of only three persistent black hole binaries that spend most of their time in the hard spectral state, the other two being Cyg X-l and 1E 1741.7-2942. It therefore provides the rare opportunity for an extensive long term study of this important black hole state which is associated with strong variability and radio jet emission. INTEGRAL has been monitoring the source since the first Galactic Center Deep Exposure season in spring 2003 during two 2-3 months long Galactic Center viewing epochs each year, amounting to 11 epochs including spring of 2008. With the exception of the last epoch quasi-simultaneous RXTE monitoring observations are available as well. Here we present an analysis of the epoch averaged broad band spectra which display considerable long term variability, most notably the occurrence of two soft/off states, extreme examples for the hysteretic behavior of black hole binaries. The hard source spectrum and long exposures allow us to extend the analysis for several epochs to approximately 800 keV using PICsIT data and address the question of the presence of a non-thermal Comptonization component.

Pottschmidt, Katja; Chernyakova, Masha; Lubinski, Piotr; Migliari, Simone; Smith, David M.; Zdziarski, Andrzej A.; Tomsick, John A.; Bezayiff, N.; Kreykenbohm, Ingo; Kretschmar, Peter; Kalemci, Emrah

2008-01-01

54

RXTE Observations of Hercules X-1 During the July 1998 Short-high State  

E-print Network

We present RXTE monitoring of the eclipsing X-ray binary Hercules X-1 conducted over the short-high state of July 1998. This was one of the last major short-high states before the source entered an anomalous low-state of activity. A comparison with previous epochs finds no evidence for special behavior during these observations. We determine orbital and pulsar spin periods to facilitate measurements period derivatives during the subsequent anomalous low state and during the next epoch of high-state activity. Spectrally, the decay of the short-high state and concurrent pre-eclipse dips are consistent with obscuration of a central X-ray source by a cloud of non-uniform column density. The standard model of a warped accretion disk of finite vertical scale height fits the characteristics of this absorber well. Pre-eclipse dips have durations a factor of a few longer than the characteristic durations of dips during main-high states. Pulse profile structure increases in complexity towards the tail of the short-high state suggesting changes in accretion curtain geometry.

Martin Still; Kieran O'Brien; Keith Horne; Danny Hudson; Bram Boroson; Saeqa Dil Vrtilek; Hannah Quaintrell; Hauke Fiedler

2001-02-06

55

Measuring the Cosmic X-ray Background With RXTE Using Lunar Occultation  

NASA Astrophysics Data System (ADS)

The Cosmic X-ray background (CXB) contains significant information about the energy content of the universe. However, the total X-ray background flux itself is still a matter of some controversy. A recent compilation of 10 CXB 2-10 keV flux measurements by Moretti et al. (2003) found statistical errors of 5%, with some values differing by up to 25%. Here we present preliminary results of a new technique to measure the X-ray background, using the dark side of the moon as an occulting shutter within the RXTE PCA field of view. This technique has the benefit of measuring the total X-ray background emission, rather than concentrating on the point-like sources. Observations were carefully designed to allow the moon to pass over the center of the PCA field of view, obscuring about 20% of the total field of view. Multiple observations throughout the year 2010, at different celestial locations, allow improved statistics and a measure of cosmic variance. In this work, we show the first results from this technique and compare to previous results, with the goal of achieving better than 5% statistical errors in the 2-10 keV band.

Markwardt, Craig; Jahoda, K.; Marshall, F.; Strohmayer, T.; Swank, J.

2011-09-01

56

Excite Assistant  

NSDL National Science Digital Library

Just when the concept of "push" technology seems like yesterday's news, Excite, Inc. produces a handy little program, the Excite Assistant, that pushes data to you without being pushy. The Excite Assistant provides you with instant access to various types of up-to-date information such as the weather for your area, the broadcast TV shows on at the moment, updated stock quotes, your horoscope, and more. The information is summarized within the Assistant's window, but when an item requires expansion, your browser is launched. By far the most useful aspect of this program is the mail notification feature. If you use Excite's Web-based mail service, the Excite Assistant, if active, will play a sound and it's icon will blink when new mail arrives. The Assistant will display the subject line and who the mail is from; clicking on the new mail loads it in your browser. Excite Assistant runs on Win95/98/NT and is free but does display small ads.

57

International Observe the Moon Night - An Opportunity to Participate in the Year of the Solar System While Sharing the Excitement of Lunar Science and Exploration with the Public  

NASA Astrophysics Data System (ADS)

International Observe the Moon Night (InOMN) is a multi-nation effort to share the excitement of recent lunar missions and new science results with education communities, amateur astronomers, space enthusiasts, and the general public. It is also intended to encourage the world to experience the thrill of observing Earth’s closest neighbor. The inaugural InOMN took place on September 18, 2010. People in over 26 countries gathered together in groups big and small to learn about the Moon through presentations by scientists, astronomers, and engineers; participate in hands-on activities; and observe the Moon through telescopes, binoculars, and the naked eye. Next year’s InOMN will take place on October 8, 2011 during the Year of the Solar System (YSS). The October 2011 YSS theme will be “Moons/Rings Across the Solar System.” InOMN is perfectly suited as an event that any museum, science center, planetarium, university, school, or other group can implement to celebrate YSS. The InOMN Coordinating Committee has developed a variety of resources and materials to make it easy to host an InOMN event of any size. Interested groups are encouraged to utilize the InOMN website (observethemoonnight.org) in planning their InOMN event for 2011/YSS. The website contains links to Moon resources, educational activities, suggestions for hosting an event, free downloads of logos and flyers for advertising an event, and contests. New for 2011 will be a discussion forum for event hosts to share their plans, tips, and experiences. Together, YSS and InOMN will enable the public to maintain its curiosity about the Moon and to gain a better understanding of the Moon’s formation, evolution, and place in the night sky.

Bleacher, L.; Daou, D.; Day, B. H.; Hsu, B. C.; Jones, A. P.; Mitchell, B.; Shaner, A. J.; Shipp, S. S.

2010-12-01

58

Focus Issue: Getting Excited About Glia  

NSDL National Science Digital Library

This Focus Issue of Science Signaling complements the Science Special Issue and highlights glial cell function, development, and disease. This issue draws attention to the molecular mechanisms of drug resistance of a cancer of glial origin, and to signaling between glia and neurons. Although glia may not be excitable, they are clearly an exciting group of cells.

Elizabeth M. Adler (American Association for the Advancement of Science; Science Signaling REV)

2010-11-09

59

An Expanded RXTE Survey of Long-Term X-ray Variability in Seyfert 1 Galaxies  

NASA Technical Reports Server (NTRS)

The first seven years of RXTE monitoring of Seyfert 1 active galactic nuclei have been systematically analyzed to yield five homogenous samples of 2-12 keV light curves, probing hard X-ray variability on successively longer durations from approx. 1 day to approx. 3.5 years. 2-10 keV variability on time scales of approx. 1 day, as probed by ASCA, are included. All sources exhibit stronger X-ray variability towards longer time scales, with variability amplitudes saturating at the longest time scales, but the increase is greater for relatively higher luminosity sources. The well-documented anticorrelation between variability amplitude and luminosity is confirmed on all time scales. However, anticorrelations between variability amplitude and black hole mass estimate are evident on only the shortest time scales probed. The data are consistent with the models of power spectral density (PSD) movement described in Markowitz et al. (2003) and McHardy et al. (2004), whereby Seyfert 1 galaxies variability can be described by a single, universal PSD shape whose cutoff frequency scales with black hole mass. The best-fitting scaling relations between variability time scale, black hole mass and X-ray luminosity support an average accretion rate of 2% of the Eddington limit for the sample. Nearly all sources exhibit stronger variability in the relatively soft 2-4 keV band compared to the 7-12 keV band on all time scales. Color-flux diagrams support also Seyfert 1s' softening as they brighten. There are indications that relatively less luminous or less massive sources exhibit a greater degree of spectral variability for a given increase in overall flux.

Markowitz, A.; Edelson, R.

2004-01-01

60

An Expanded RXTE Survey of X-ray Variability in Seyfert 1 Galaxies  

E-print Network

The first seven years of RXTE monitoring of Seyfert 1 active galactic nuclei have been systematically analyzed to yield five homogeneous samples of 2-12 keV light curves, probing hard X-ray variability on successively longer durations from ~1 day to ~3.5 years. 2-10 keV variability on time scales of ~1 day, as probed by ASCA, are included. All sources exhibit stronger X-ray variability towards longer time scales, but the increase is greater for relatively higher luminosity sources. Variability amplitudes are anti-correlated with X-ray luminosity and black hole mass, but amplitudes saturate and become independent of luminosity or black hole mass towards the longest time scales. The data are consistent with the models of power spectral density (PSD) movement described in Markowitz et al. (2003a) and McHardy et al. (2004), whereby Seyfert 1 galaxies' variability can be described by a single, universal PSD shape whose break frequency scales with black hole mass. The best-fitting scaling relations between variability time scale, black hole mass and X-ray luminosity imply an average accretion rate of ~5% of the Eddington limit for the sample. Nearly all sources exhibit stronger variability in the relatively soft 2-4 keV band compared to the 7-12 keV band on all time scales. There are indications that relatively less luminous or less massive sources exhibit a greater degree of spectral variability for a given increase in overall flux.

Alex Markowitz; Rick Edelson

2004-09-02

61

RXTE Observations of the Seyfert 2 Galaxy MrK 348  

NASA Technical Reports Server (NTRS)

We present RXTE monitoring observations of the Seyfert 2 galaxy Mrk 348 spanning a 6 month period. The time-averaged spectrum in the 3-20 keV band shows many features characteristic of a Compton-thin Seyfert 2 galaxy, namely a hard underlying power-law continuum (Gamma approximately equal 1.8) with heavy soft X-ray absorption (N(sub H) approximately 10(exp 23)/sq cm) plus measurable iron K.alpha emission (equivalent width approximately 100 eV) and, at high energy, evidence for a reflection component (R approximately < 1). During the first half of the monitoring period the X-ray continuum flux from Mrk 348 remained relatively steady. However this was followed by a significant brightening of the source (by roughly a factor of 4) with the fastest change corresponding to a doubling of its X-ray flux on a timescale of about 20 days. The flux increase was accompanied by a marked softening of X-ray spectrum most likely attributable to a factor approximately 3 decline in the intrinsic line-of-sight column density. In contrast the iron K.alpha line and the reflection components showed no evidence of variability. These observations suggest a scenario in which the central X-ray source is surrounded by a patchy distribution of absorbing material located within about a light-week of the nucleus of Mrk 348. The random movement of individual clouds within the absorbing screen, across our line of sight, produces substantial temporal variations in the measured column density on timescales of weeks to months and gives rise to the observed X-ray spectral variability. However, as viewed from the nucleus the global coverage and typical thickness of the cloud layer remains relatively constant.

Smith, David A.; Georgantopoulos, Ioannis; Warwick, Robert S.

2000-01-01

62

Excited Insects  

E-print Network

but not killing them doesn't actually count as true celebration. Now, China. There's a country that knows how to make a bug feel good. Bugs have their very own holiday in the Chinese calendar. It's called the Feast of the Excited Insects and it falls on March 5th...

Hacker, Randi

2011-04-06

63

Testing 3D SPH Models Of Eta Carina's Winds By HST, RXTE, VLT And VLTI Observations  

NASA Astrophysics Data System (ADS)

Observations of Eta Carina have been combined with three-dimensional smoothed-particle hydrodynamic (3DSPH) simulations providing considerable insight on this >100 Mo binary that may become near-term supernovae, a GRB, or a staid WR binary. Understanding how this system loses 1e-3 Mo/yr, 500 km/s will provide new understanding of massive stellar evolution, including the first progenitors of GRBs, supernovae and pseudo-supernovae. The 3DSPH models extend to 100 semi-major axes ( 2000 AU, <2” at 2300 pc). At these scales, HST/STIS resolves [Fe III] and [Fe II] spatial-velocity structures that change with orbital phase and position angle. Radiative transfer models combining temperature and density with EtaCar B's FUV lead to synthetic spectroimages of extended wind-wind interfaces. Model X-ray light curves provide orbital inclination and location of periastron but cannot determine sky PA. Synthetic spectro-images generated for a range of possible binary orientations lead to best-fit when the orbital axis is closely aligned with the Homunculus axis of symmetry, and periastron with EtaCar B on the far side of EtaCar A. VLTI/AMBER measures of the continuum, extended hydrogen and helium structures of EtaCar A demonstrate that, across periastron, EtaCar B penetrates the primary extended atmosphere. Spectroimagery observations of He 10830 by VLT/CRIRES show blue-shifted emission extending to -1500 km/s, consistent with wind-wind structures driven by the companion's fast wind. The 2009.0 RXTE X-ray recovery and return of the spectroscopic high state was much sooner than the 1998.0 and 2003.5 recoveries. What has changed? Suggestions range from a drop in the primary wind, changes in the secondary wind or line-of-sight shifting of the wind-wind boundary. We will discuss potential observational tests based upon predictions by 3DSPH models.

Gull, Theodore R.; Madura, T.; Groh, J.; Weigelt, G.; Corcoran, M.; Owocki, S.; Russell, C.; Okazaki, A.

2011-01-01

64

RXTE Observation of 4U 1630-47 During its 1998 Outburst  

NASA Technical Reports Server (NTRS)

During the 1998 outburst of 4U 1630-47 it was extensively observed with the Rossi X-ray Timing Explorer (RXTE). In order to cover the outburst more thoroughly our data (Obs. ID: 30178-0[1-2]- ) were combined with those of Cui et al. (Obs. ID: 30188-02-). These observations were later compared with the complementary observations. Power density and energy spectra have been made for each observation. The data was used to place radio and hard X-ray observations within context. Analysis of SAX (Satellite per Astronomia a raggi X) and BATSE (Burst and Transient Source Experiment) data was also included within the study. The count rate and position in hardness-intensity, color-color diagrams and simple spectral fits are used to track the concurrent spectral changes. The source showed seven distinct types of timing behavior, most of which show differences with the canonical black hole spectral/timing states. In marked contrast to previous outbursts, we find quasi-periodic oscillation (QPO) signals during nearly all stages of the outburst with frequencies between 0.06 Hz and 14 Hz and a remarkable variety of other characteristics. In particular we find large (up to 23% rms) amplitude QPO on the early rise. Later, slow 0.1 Hz semi- regular short (- 5 sec), 9 to 16% deep dips dominate the light curve. At this time there are two QPOS, one stable near 13.5 Hz and the other whose frequency drops from 6-8 Hz to - 4.5 Hz during the dips. BeppoSAX observations during the very late declining phase show 4U 1630-47 in a low state. These results will shortly be published. We are completing a detailed analysis of the energy spectra (in preparation). The QPO/noise properties are being correlated with the concurrent spectral changes. Detailed studies of the QPO are being undertaken using sophisticated timing analysis methods. Finally a comparison with the other outbursts of 1630-47 is being made.

Dieters, Stefan W.

1999-01-01

65

RXTE and BeppoSAX Observations of MCG-5-23-16: Reflection From Distant Cold Material  

NASA Technical Reports Server (NTRS)

We examine the spectral variability of the Seyfert 1.9 galaxy MCG-5-23-16 using RXTE and BeppoSAX observations spanning 2 years from April 1996 to April 1998. During the first year the X-ray source brightens by a factor of approximately 25% on timescales of days to months. During this time, the reprocessed continuum emission seen with RXTE does not respond measurably to the continuum increase. However, by the end of the second year during the BeppoSAX epoch the X-ray source has faded again. This time, the reprocessed emission has also faded, indicating that the reprocessed flux has responded to the continuum. If these effects are caused by time delays due to the distance between the X-ray source and the reprocessing region, we derive a light crossing time of between approximately 1 light day and approximately 1.5 light years. This corresponds to a distance of 0.001 pc to 0.55 pc, which implies that the reprocessed emission originates between 3 x 10(exp 15) cm and 1.6 x 10(exp l8) cm from the X-ray source. In other words, the reprocessing in MCG-5-23-16 is not dominated by the inner regions of a standard accretion disk.

Mattson, B. J.; Weaver, K. A.

2003-01-01

66

Experience Gained From Launch and Early Orbit Support of the Rossi X-Ray Timing Explorer (RXTE)  

NASA Technical Reports Server (NTRS)

this paper reports the results to date of early mission support provided by the personnel of the Goddard Space Flight Center Flight Dynamics Division (FDD) for the Rossi X-Ray Timing Explorer (RXTE) spacecraft. For this mission, the FDD supports onboard attitude determination and ephemeris propagation by supplying ground-based orbit and attitude solutions and calibration results. The first phase of that support was to provide launch window analyses. As the launch window was determined, acquisition attitudes were calculated and calibration slews were planned. postlaunch, these slews provided the basis for ground determined calibration. Ground determined calibration results are used to improve the accuracy of onboard solutions. The FDD is applying new calibration tools designed to facilitate use of the simultaneous, high-accuracy star observations from the two RXTE star trackers for ground attitude determination and calibration. An evaluation of the performance of these tools is presented. The FDD provides updates to the onboard star catalog based on preflight analysis and analysis of flight data. The in-flight results of the mission support in each area are summarized and compared with pre-mission expectations.

Fink, D. R.; Chapman, K. B.; Davis, W. S.; Hashmall, J. A.; Shulman, S. E.; Underwood, S. C.; Zsoldos, J. M.; Harman, R. R.

1996-01-01

67

Long-Term RXTE Monitoring of the Anomalous X-ray Pulsar 1E 1048.1-5937  

E-print Network

We report on long-term monitoring of the anomalous X-ray pulsar (AXP) 1E 1048.1-5937 using the Rossi X-ray Timing Explorer (RXTE). The timing behavior of this pulsar is different from that of other AXPs being monitored with RXTE. In particular, we show that the pulsar shows significant deviations from simple spin-down such that phase-coherent timing has not been possible over time spans longer than a few months. We find that the deviations from simple spin down are not consistent with single "glitch" type events, nor are they consistent with radiative precession. We show that in spite of the rotational irregularities, the pulsar exhibits neither pulse profile changes nor large pulsed flux variations. We discuss the implications of our results for AXP models. In the context of the magnetar model, we suggest that 1E 1048.1-5937 may be a transition object between the soft gamma-ray repeater and AXP populations, and the AXP most likely to one day undergo an outburst.

Victoria M. Kaspi; Fotis P. Gavriil; Deepto Chakrabarty; Jessica R. Lackey; Michael P. Muno

2001-07-16

68

Disk-dominated States of 4U 1957+11: Chandra, XMM-Newton, and RXTE Observations of Ostensibly the Most Rapidly Spinning Galactic Black Hole  

E-print Network

We present simultaneous Chandra High-Energy Transmission Gratings (HETG) and Rossi X-ray Timing Explorer (RXTE) observations of a "soft state" of the black hole candidate 4U 1957+11. These spectra, having limited hard X-ray ...

Nowak, Michael A.

69

A Second Look at the Accretion Disk Wind in GRS 1915+015 as Observed with Chandra and RXTE  

NASA Astrophysics Data System (ADS)

We present a re-analysis of simultaneous Chandra and RXTE observations of the microquasar GRS 1915+015 observed in a soft state first presented by Ueda et al. (2009). In our extended analysis, we incorporate a number of previously unpublished highly ionized absorption lines above 7.5 keV, as well as self-consistent relativistic reflection models, updated ISM cross-sections, and detailed XSTAR photoionization models for a self-consistent treatment of the continuum and the accretion disk wind. Through a time-resolved spectral analysis, we confirm and tightly constrain the ionization parameter and column density variability of the wind during the observations. We discuss properties of the wind, including its evolution and mass loss rate, and the relationship between accretion, ejection, and ionization processes revealed by our updated modeling.

Keck, Mason; Neilsen, Joseph

2015-01-01

70

A Study of the New X-ray Transient RXTE J2123-058 during its Post-Outburst State  

E-print Network

We carried out I, R, V and B photometric observations of the neutron star X-ray binary RXTE J2123-058 shortly after the end of the X-ray outburst in mid-1998. We adopt the low mass binary model to interpret our observations. After folding our data on the 0.24821-d orbital period, and correcting for the steady brightness decline following the outburst, we observe sinusoidal oscillations with hints of ellipsoidal modulations which became progressively more evident. Our data also show that the decline in brightness was faster in the V band than in the R and I bands. This suggests both the cooling of an irradiation-heated secondary star and the fading of an accretion disc over the nights of our observations.

Roberto Soria; Kinwah Wu; Duncan Galloway

1999-06-16

71

Modelling the RXTE light curve of ? Carinae from a 3D SPH simulation of its binary wind collision  

NASA Astrophysics Data System (ADS)

The very massive star system ? Carinae exhibits regular 5.54 yr (2024 d) period disruptive events in wavebands ranging from the radio to X-ray. There is a growing consensus that these events likely stem from periastron passage of an (as yet) unseen companion in a highly eccentric (e ~ 0.9) orbit. This Letter presents 3D smoothed particle hydrodynamics (SPH) simulations of the orbital variation of the binary wind-wind collision, and applies these to modelling the X-ray light curve observed by the Rossi X-ray Timing Explorer (RXTE). By providing a global 3D model of the phase variation of the density of the interacting winds, the simulations allow computation of the associated variation in X-ray absorption, presumed here to originate from near the apex of the wind-wind interaction cone. We find that the observed RXTE light curve can be readily fitted if the observer's line of sight is within this cone along the general direction of apastron. Specifically, the data are well fitted by an assumed inclination i = 45° for the orbit's polar axis, which is thus consistent with orbital angular momentum being along the inferred polar axis of the Homunculus nebula. The fits also constrain the position angle ? that an orbital-plane projection makes with the apastron side of the semimajor axis, strongly excluding positions ? < 9° along or to the retrograde side of the axis, with the best-fitting position given by ? = 27°. Overall the results demonstrate the utility of a fully 3D dynamical model for constraining the geometric and physical properties of this complex colliding wind binary system.

Okazaki, A. T.; Owocki, S. P.; Russell, C. M. P.; Corcoran, M. F.

2008-07-01

72

Comprehensive Analysis of RXTE Data from Cyg X-1. Spectral Index-Quasi-Periodic Oscillation Frequency-Luminosity Correlations  

NASA Technical Reports Server (NTRS)

We present timing and spectral analysis of approx. 2.2 Ms of Rossi X-ray Time Explorer (RXTE) archival data from Cyg X-1. Using the generic Comptonization model we reveal that the spectrum of Cyg X-1 consists of three components: a thermal seed photon spectrum, a Comptonized part of the seed photon spectrum and the iron line. We find a strong correlation between 0.1-20 Hz frequencies of quasiperiodic oscillations (QPOs) and the spectral power-law index. Presence of two spectral phases (states) are clearly seen in the data when the spectral indices saturate at low and high values of QPO frequencies. This saturation effect was discovered earlier in a number of black hole candidate (BHC) sources and now we strongly confirm this phenomenon in Cyg X-1. In the soft state this index- QPO frequency correlation shows a saturation of the photon index Gamma approx. 2.1 at high values of the low frequency upsilon(sub L). The saturation level of Gamma approx. 2.1 is the lowest value found yet in BHCs. The bolometric luminosity does not show clear correlation with the index. We also show that Fe K(sub alpha) emission line strength (equivalent width, EW) correlates with the QPO frequency. EW increases from 200 eV in the low/hard state to 1.5 keV in the high/soft state. The revealed observational correlations allow us to propose a scenario for the spectral transition and iron line formation which occur in BHC sources. We also present the spectral state (the power-law index) evolution for eight years of Cyg X-1 observations by RXTE.

Shaposhnikov, Nickolai; Titarchuk, Lev

2006-01-01

73

Big Ideas: Creativity, Design and Innovation Camp Photo Permission Venture Engineering and Science at McMaster University is excited to offer, for the first  

E-print Network

Big Ideas: Creativity, Design and Innovation Camp Photo Permission Form Venture Engineering and Innovation Camp. This is a new program from Venture Engineering and Science and Actua programs. Venture/children. YES, I give permission for Venture Engineering and Science and Actua to take photos, video and audio

Haykin, Simon

74

Structure of the Circumnuclear Region of Seyfert 2 Galaxies Revealed by RXTE Hard X-Ray Observations of NGC 4945  

NASA Technical Reports Server (NTRS)

NGC 4945 is one of the brightest Se.yfert galaxies on the sky at 100 keV, but is completely absorbed below 10 keV, implying an optical depth of the absorber to electron scattering of a few; its absorption column is probably the largest which still allows a direct view of the nucleus at hard X-ray energies. Our observations of it with the Rossi X-ray Timing Explorer (RXTE) satellite confirm the large absorption, which for a simple phenomenological fit using an absorber with Solar abundances implies a column of 4.5(sup 0.4, sub -0.4) x 10(exp 24) /sq cm. Using a a more realistic scenario (requiring Monte Carlo modeling of the scattering), we infer the optical depth to Thomson scattering of approximately 2.4. If such a scattering medium were to subtend a large solid angle from the nucleus, it should smear out any intrinsic hard X-ray variability on time scales shorter than the light travel time through it. The rapid (with a time scale of approximately a day) hard X-ray variability of NGC 4945 we observed with the RXTE implies that the bulk of the extreme absorption in this object does not originate in a parsec-size, geometrically thick molecular torus. Limits on the amount of scattered flux require that the optically thick material on parsec scales must be rather geometrically thin, subtending a half-angle < 10 deg. This is only marginally consistent with the recent determinations of the obscuring column in hard X-rays, where only a quarter of Seyfert 2s have columns which are optically thick, and presents a problem in accounting for the Cosmic X-ray Background primarily with AGN possessing the geometry as that inferred by us. The small solid angle of the obscuring material, together with the black hole mass (of approximately 1.4 x 10(exp 6) solar mass) from megamaser measurements. allows a robust determination of the source luminosity, which in turn implies that the source radiates at approximately 10% of the Eddington limit.

Madejski, G.; Zycki, P.; Done, C.; Valinia, A.; Blanco, P.; Rothschild, R.; Turek, B.

2000-01-01

75

TeV and X-ray Monitoring of LS I +61 303 With VERITAS, Swift, and RXTE  

E-print Network

Between September 2006 and February 2007, the galactic binary LS I +61 303 was monitored in the TeV band with the VERITAS array of imaging Cherenkov telescopes. These observations confirm LS I +61 303 as a variable TeV gamma-ray source, with emission peaking between orbital phase 0.6 and 0.7. During this observational period, monitoring in the X-ray regime was also carried out using both the RXTE and Swift detectors, which offered complementary coverage of the source. Outbursts in the 0.2-10 keV band were observed by both satellites at close to the same orbital phase as the TeV peak during the 2 orbital cycles covered simultaneously in both bands. While this source has been extensively studied in the X-ray band in the past, this is the first observational campaign to utilize contemporaneous X-ray and TeV data on LS I +61 303.

VERITAS Collaboration; A. Smith

2007-09-27

76

RXTE, VLBA, Optical, and Radio Monitoring of the Quasars 3C 279, PKS 1510--089, and 3C 273  

NASA Technical Reports Server (NTRS)

We are continuing our combined RXTE X-ray, VLBA imaging (at 43 GHz), optical (several observatories), and radio (University of Michigan Radio Astronomy Observatory) monitoring of the quasars 3C 279 and PKS 1510-089, and have started similar monitoring of 3C 273. X-ray flares in 3C 279 and PKS 1510-089 are associated with ejections of superluminal components. In addition, there is a close connection between the optical and X-ray variability of 3C 279. There is a strong correlation between the 14.5 GHz and X-ray variability of PKS 1510-089 in 1997 and 1998 (with the radio leading the X-ray) that becomes weaker in subsequent years. X-ray fluctuations occur on a variety of timescales in 3C 273, with a major prolonged outburst in mid-2001. The lead author will discuss the correlations in terms of inverse Compton models for the X-ray emission coupled with synchrotron models for the lower-frequency radiation. Synchrotron self-Compton models can explain the "reverse" time lag in PKS 1510-089 is well as the variable correlation between the X-ray variations and those at lower frequencies in this object and in 3C 279.

Marscher, A. P.; Jorstad, S. G.; Aller, M. F.; McHardy, I. M.; Balonek, T. J.

2001-01-01

77

Science.  

ERIC Educational Resources Information Center

This document contains the following papers on science instruction and technology: "A 3-D Journey in Space: A New Visual Cognitive Adventure" (Yoav Yair, Rachel Mintz, and Shai Litvak); "Using Collaborative Inquiry and Interactive Technologies in an Environmental Science Project for Middle School Teachers: A Description and Analysis" (Patricia…

Roach, Linda E., Ed.

78

Montana State University 1 Computer Science  

E-print Network

Montana State University 1 Computer Science A computer science degree is highly curriculum is designed with considerable flexibility, due to the numerous types of computer science jobs. Students may then select from exciting computer science electives such as artificial intelligence

Maxwell, Bruce D.

79

ALGEBRA SEMINAR TALK Department of Computer Science  

E-print Network

ALGEBRA SEMINAR TALK WITH LILA KARI Department of Computer Science The University of Western for Theoretical Computer Science" Abstract: We are now witnessing exciting interactions between computer science absorbing notions, techniques and methodologies intrinsic to computer science and mathematics, theoretical

Sinnamon, Gordon J.

80

Discovery and Monitoring of a New Black Hole Candidate XTE J1752-223 with RXTE: RMS Spectrum Evolution, BH Mass and the Source Distance  

NASA Technical Reports Server (NTRS)

We report on the discovery and monitoring observations of a new galactic black hole candidate XTE J1752-223 by Rossi X-ray Timing Explorer (RXTE). The new source appeared on the X-ray sky on October 21 2009 and was active for almost 8 months. Phenomenologically, the source exhibited the low-hard/highsoft spectral state bi-modality and the variability evolution during the state transition that matches standard behavior expected from a stellar mass black hole binary. We model the energy spectrum throughout the outburst using a generic Comptonization model assuming that part of the input soft radiation in the form of a black body spectrum gets reprocessed in the Comptonizing medium. We follow the evolution of fractional root-mean-square (RMS) variability in the RXTE/PCA energy band with the source spectral state and conclude that broad band variability is strongly correlated with the source hardness (or Comptonized fraction). We follow changes in the energy distribution of rms variability during the low-hard state and the state transition and find further evidence that variable emission is strongly concentrated in the power-law spectral component. We discuss the implication of our results to the Comptonization regimes during different spectral states. Correlations of spectral and variability properties provide measurements of the BH mass and distance to the source. The spectral-timing correlation scaling technique applied to the RXTE observations during the hardto- soft state transition indicates a mass of the BH in XTE J1752-223 between 8 and 11 solar masses and a distance to the source about 3.5 kiloparsec.

Shaposhinikov, Nikolai; Markwardt, Craig; Swank, Jean; Krimm, Hans

2010-01-01

81

Disk Dominated States of 4U 1957+11: Chandra, XMM, and RXTE Observations of Ostensibly the Most Rapidly Spinning Galactic Black Hole  

E-print Network

We present simultaneous Chandra-HETG and RXTE observations of a moderate flux `soft state' of the black hole candidate 4U1957+11. These spectra, having a minimally discernible hard X-ray excess, are an excellent test of modern disk atmosphere models that include the effects of black hole spin. The HETG data show that the soft disk spectrum is only very mildly absorbed with N_H =1-2 X 10^{21} cm^-2. These data additionally reveal 13.449 A NeIX absorption consistent with the warm/hot phase of the interstellar medium. The fitted disk model implies a highly inclined disk around a low mass black hole rapidly rotating with normalized spin a*~1. We show, however, that pure Schwarzschild black hole models describe the data extremely well, albeit with large disk atmosphere ``color-correction'' factors. Standard color-correction factors can be attained if one additionally incorporates mild Comptonization. We find that the Chandra observations do not uniquely determine spin. Similarly, XMM/RXTE observations, taken only six weeks later, are equally unconstraining. This lack of constraint is partly driven by the unknown mass and unknown distance of 4U1957+11; however, it is also driven by the limited bandpass of Chandra and XMM. We therefore present a series of 48 RXTE observations taken over the span of several years and at different brightness/hardness levels. These data prefer a spin of a*~1, even when including a mild Comptonization component; however, they also show evolution of the disk atmosphere color-correction factors. If the rapid spin models with standard atmosphere color-correction factors of h_d=1.7 are to be believed, then the RXTE observations predict that 4U1957+11 can range from a 3 M_sun black hole at 10 kpc with a*~0.83 to a 16 M_sun black hole at 22 kpc with a* ~ 1, with the latter being statistically preferred.

Michael A. Nowak; Adrienne Juett; Jeroen Homan; Yangsen Yao; Joern Wilms; Norbert S. Schulz; Claude R. Canizares

2008-09-17

82

Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State  

NASA Technical Reports Server (NTRS)

Using Suzaku and the Rossi X-ray Timing Explorer (RXTE), we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard "low states". Additionally, all of these observations occurred near superior conjunction with our line of sight to the X-ray source passing through the dense phases of the "focused wind" from the mass donating secondary. One of our observations was also simultaneous with observations by the Chandra-High Energy Transmission Grating (HETG). These latter spectra are crucial for revealing the ionized absorption due to the secondary s focused wind. Such absorption is present and must be accounted for in all four spectra. These simultaneous data give an unprecedented view of the 0.8-300 keV spectrum of Cyg X-1, and hence bear upon both corona and X-ray emitting jet models of black hole hard states. Three models fit the spectra well: coronae with thermal or mixed thermal/non-thermal electron populations, and jets. All three models require a soft component that we fit with a low temperature disk spectrum with an inner radius of only a few tens of GM/c2. All three models also agree that the known spectral break at 10 keV is not solely due to the presence of reflection, but each gives a different underlying explanation for the augmentation of this break. Thus whereas all three models require that there is a relativistically broadened Fe line, the strength and inner radius of such a line is dependent upon the specific model, thus making premature line-based estimates of the black hole spin in the Cyg X-1 system. We look at the relativistic line in detail, accounting for the narrow Fe emission and ionized absorption detected by HETG. Although the specific relativistic parameters of the line are continuum-dependent, none of the broad line fits allow for an inner disk radius that is > 40 GM/c(sup 2).

Nowak, Michael A.; Hanke, Manfred; Trowbridge, Sarah N.; Markoff, Sera B.; Wilms, Joern; Pottschmidt, Katja; Coppi, Paolo; Maitra, Dipankar; Davis, Jhn E.; Tramper, Frank

2009-01-01

83

RXTE All-Sky Slew Survey. Catalog of X-Ray Sources at B Greater Than 10 deg  

NASA Technical Reports Server (NTRS)

We report results of a serendipitous hard X-ray (3-20 keV), nearly all-sky (absolute value of b greater than l0 deg.) survey based on RXTE/PCA observations performed during satellite reorientations in 1996-2002. The survey is 80% (90%) complete to a 4(sigma) limiting flux of approx. = 1.8 (2.5) x 10(exp -l1) erg/s sq cm in the 3-20 keV band. The achieved sensitivity in the 3-8 keV and 8-20 keV subbands is similar to and an order of magnitude higher than that of the previously record HEAO-1 A1 and HEAO-1 A4 all-sky surveys, respectively. A combined 7 x 10(exp 3) sq. deg area of the sky is sampled to flux levels below l0(exp -11) erg/ s sq cm (3-20 keV). In total 294 sources are detected and localized to better than 1 deg. 236 (80%) of these can be confidently associated with a known astrophysical object; another 22 likely result from the superposition of 2 or 3 closely located known sources. 35 detected sources remain unidentified, although for 12 of these we report a likely soft X-ray counterpart from the ROSAT all-sky survey bright source catalog. Of the reliably identified sources, 63 have local origin (Milky Way, LMC or SMC), 64 are clusters of galaxies and 100 are active galactic nuclei (AGN). The fact that the unidentified X-ray sources have hard spectra suggests that the majority of them are AGN, including highly obscured ones (N(sub H) greater than l0(exp 23)/sq cm). For the first time we present a log N-log S diagram for extragalactic sources above 4 x l0(exp -12) erg/ s sq cm at 8-20 keV. Key words. cosmo1ogy:observations - diffuse radiation - X-rays general

Revnivtsev, M.; Sazonov, S.; Jahoda, K.; Gilfanov, M.

2004-01-01

84

Acoustically excited heated jets. 1: Internal excitation  

NASA Technical Reports Server (NTRS)

The effects of relatively strong upstream acoustic excitation on the mixing of heated jets with the surrounding air are investigated. To determine the extent of the available information on experiments and theories dealing with acoustically excited heated jets, an extensive literature survey was carried out. The experimental program consisted of flow visualization and flowfield velocity and temperature measurements for a broad range of jet operating and flow excitation conditions. A 50.8-mm-diam nozzle was used for this purpose. Parallel to the experimental study, an existing theoretical model of excited jets was refined to include the region downstream of the jet potential core. Excellent agreement was found between theory and experiment in moderately heated jets. However, the theory has not yet been confirmed for highly heated jets. It was found that the sensitivity of heated jets to upstream acoustic excitation varies strongly with the jet operating conditions and that the threshold excitation level increases with increasing jet temperature. Furthermore, the preferential Strouhal number is found not to change significantly with a change of the jet operating conditions. Finally, the effects of the nozzle exit boundary layer thickness appear to be similar for both heated and unheated jets at low Mach numbers.

Lepicovsky, J.; Ahuja, K. K.; Brown, W. H.; Salikuddin, M.; Morris, P. J.

1988-01-01

85

Swift/BAT and RXTE Observations of the Peculiar X-ray Binary 4U 2206+54 - Disappearance of the 9.6 Day Modulation  

NASA Technical Reports Server (NTRS)

Observations of the high-mass X-ray binary 4U 2206+54 with the Swift Burst Alert Telescope (BAT) do not show modulation at the previously reported period of 9.6 days found from observations made with the Rossi X-ray Timing Explorer (RXTE) All-Sky Monitor (ASM). Instead, the strongest peak in the power spectrum of the BAT light curve occurs at a period of 19.25+/-0.08 days, twice the period found with the RXTE ASM. The maximum of the folded BAT light curve is also delayed compared to the maximum of the folded ASM light curve. The most recent ASM data folded on twice the 9.6 day period show 'similar morphology to the folded BAT light curve. This suggests that the apparent period doubling is a recent secular change rather than an energy-dependent effect. The 9.6 day period is thus not a permanent strong feature of the light curve. We suggest that the orbital period of 4U 2206+54 may be twice the previously proposed value.

Corbet, R. H. D.; Markwardt, C.; Tueller, J.

2007-01-01

86

Revisit to the RXTE and ASCA Data for GRO J1655-40: Effects of Radiative Transfer in Corona and Color Hardening in the Disk  

NASA Technical Reports Server (NTRS)

The results of spectral modeling of the data for a series of RXTE observations and four ASCA observations of GRO J1655-40 are presented. The thermal Comptonization model is used instead of the power-law model for the hard component of the two-component continuum spectra. The previously reported dramatic variations of the apparent inner disk radius of GRO J1655-40 during its outburst may be due to the inverse Compton scattering in the hot corona. A procedure is developed for making the radiative transfer correction to the fitting parameters from RXTE data and a more stable inner disk radius is obtained. A practical process of determining the color correction (hardening) factor from observational data is proposed and applied to the four ASCA observations of GRO J1655-40. We found that the color correction factor may vary significantly between different observations and the finally corrected physical inner disk radius remains reasonably stable over a large range of luminosity and spectral states.

Zhang, S. Nan; Zhang, Xiaoling; Wu, Xuebing; Yao, Yangsen; Sun, Xuejun; Xu, Haiguang; Cui, Wei; Chen, Wan; Harmon, B. A.; Robinson, C. R.

1999-01-01

87

NASA and Mary J. Blige Encourage Exciting Careers For Women - Duration: 0:43.  

NASA Video Gallery

NASA is collaborating with award-winning recording artist Mary J. Blige to encourage young women to pursue exciting experiences and career choices through studying science, technology, engineering ...

88

8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER No. 2., AND GENERATOR UNITS BEHIND EXCITER No. 2 IN BACKGROUND. EXCITER No. 1 GENERATOR HAS A COVER OVER TOP HALF OF COMMUTATOR ELEMENT. VIEW TO NORTHWEST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

89

Events | Physical Sciences in Oncology  

Cancer.gov

The 2015 AAAS Annual Meeting will include exciting work at the intersection of the physical and life sciences, including two sessions organized by NCI Physical Sciences-Oncology Network (PS-ON) Program Directors.

90

Systems Science  

ERIC Educational Resources Information Center

Scholars representing the field of systems science were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might change our understanding. The scholars included Alexander Christakis, Debora Hammond, Michael Jackson, Alexander Laszlo, Ian Mitroff, Dave…

Christakis, Alexander; Hammond, Debora; Jackson, Michael; Laszlo, Alexander; Mitroff, Ian; Snowden, Dave; Troncale, Len; Carr-Chellman, Alison; Spector, J. Michael; Wilson, Brent

2013-01-01

91

Organizational Science  

ERIC Educational Resources Information Center

Scholars representing the field of organizational science, broadly defined as including many fields--organizational behavior and development, management, workplace performance, and so on--were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might…

Beriwal, Madhu; Clegg, Stewart; Collopy, Fred; McDaniel, Reuben, Jr.; Morgan, Gareth; Sutcliffe, Kathleen; Kaufman, Roger; Marker, Anthony; Selwyn, Neil

2013-01-01

92

Femtosecond Timescale Evolution of Pyrrole Electronic Excitation  

NASA Astrophysics Data System (ADS)

Pyrrole is a simple aromatic molecule with relevantchromophoric properties in biology. Although its apparent simplicity, it shows a complicated dynamics after excitation in the near part of the UV absorption spectrum, which results from the interplay between the bright ??^* and the dark dissociative ??^* electronic transitions. Herein, we present a time resolved study with ultrafast resolution on the relaxation dynamics of isolated pyrrole, after excitation in the 265-217 nm range. Two lifetimes of 19 and 15 fs, which are associated with the internal conversion from the bright 1B2 ??^* state and the propagation of the wavepacket on the ??^* state, respectively, are found in the studied energy interval. The work also explores the consequences of non resonant adiabatic excitation of the system when broadband femtosecond pulses are employed to prepare the molecule in the targeted electronic states, revealing the key implication of this type of coherent phenomena. The collected data reveal that the bright 1B2 ??^* state is adiabatically populated at excitation wavelengths far away from resonance, providing an efficient way to reach the ??^* state. The recorded transients are fit employing a coherent model that provides a comprehensive view of the dynamical processes pyrrole undergoes after excitation by ultrashort light pulses. M. N. R. Ashfold, B. Cronin, A. L. Devine, R. N. Dixon and M. G. D. Nix Science, 312, 1637-1640, 2006.

Montero, Raul; Conde, Alvaro Peralta; Ovejas, Virginia; Castano, Fernando; Longarte, Asier

2012-06-01

93

Electronic excitations of fluoroethylenes  

NASA Astrophysics Data System (ADS)

Several lowest-lying singlet electronic states of vinyl fluoride, trans-, cis-, and 1,1-difluoroethylene, trifluoroethylene, and tetrafluoroethylene were investigated by using symmetry-adapted cluster configuration interaction theory. Basis sets up to Dunning's aug-cc-pVTZ augmented with appropriate Rydberg functions were utilized for the calculations. Calculated excitation energies show a good agreement with the available experimental values. Even in the troublesome ? ??* transitions, the excitation energies obtained in the present study agree well with the experimental values except in one or two fluoroethylenes. Strong mixing between different states was noticed in a few fluoroethylenes; especially the mixing is very strong between ?-? * and ?-3p? states in trifluoroethylene. No pure ?-? * excited state was found in almost all the fluoroethylenes. Several assignments and reassignments of features in the experimental spectra were suggested. The present study does not support the existing argument that the interaction between the ?-? * and ?-? * states is the reason behind the blueshift of around 1.25eV in the ?-?* excitation energy of tetrafluoroethylene. Possible reasons, including structural changes, for this shift are discussed in detail. Several low-lying triplet excited states were also studied.

Arulmozhiraja, Sundaram; Ehara, Masahiro; Nakatsuji, Hiroshi

2007-01-01

94

Electronic excitations of fluoroethylenes.  

PubMed

Several lowest-lying singlet electronic states of vinyl fluoride, trans-, cis-, and 1,1-difluoroethylene, trifluoroethylene, and tetrafluoroethylene were investigated by using symmetry-adapted cluster configuration interaction theory. Basis sets up to Dunning's aug-cc-pVTZ augmented with appropriate Rydberg functions were utilized for the calculations. Calculated excitation energies show a good agreement with the available experimental values. Even in the troublesome pi-->pi(*) transitions, the excitation energies obtained in the present study agree well with the experimental values except in one or two fluoroethylenes. Strong mixing between different states was noticed in a few fluoroethylenes; especially the mixing is very strong between pi-pi(*) and pi-3ppi states in trifluoroethylene. No pure pi-sigma(*) excited state was found in almost all the fluoroethylenes. Several assignments and reassignments of features in the experimental spectra were suggested. The present study does not support the existing argument that the interaction between the pi-pi(*) and sigma-sigma(*) states is the reason behind the blueshift of around 1.25 eV in the pi-pi(*) excitation energy of tetrafluoroethylene. Possible reasons, including structural changes, for this shift are discussed in detail. Several low-lying triplet excited states were also studied. PMID:17286469

Arulmozhiraja, Sundaram; Ehara, Masahiro; Nakatsuji, Hiroshi

2007-01-28

95

Exciting flavored bound states  

NASA Astrophysics Data System (ADS)

We study ground and radial excitations of flavor singlet and flavored pseudoscalar mesons within the framework of the rainbow-ladder truncation using an infrared massive and finite interaction in agreement with recent results for the gluon-dressing function from lattice QCD and Dyson-Schwinger equations. Whereas the ground-state masses and decay constants of the light mesons as well as charmonia are well described, we confirm previous observations that this truncation is inadequate to provide realistic predictions for the spectrum of excited and exotic states. Moreover, we find a complex conjugate pair of eigenvalues for the excited D(s) mesons, which indicates a non-Hermiticity of the interaction kernel in the case of heavy-light systems and the present truncation. Nevertheless, limiting ourselves to the leading contributions of the Bethe-Salpeter amplitudes, we find a reasonable description of the charmed ground states and their respective decay constants.

Rojas, E.; El-Bennich, B.; de Melo, J. P. B. C.

2014-10-01

96

Multi-photon excitation microscopy  

PubMed Central

Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase their impact in areas such biotechnology, neurobiology, embryology, tissue engineering, materials science where imaging can be coupled to the possibility of using the microscopes in an active way, too. As well, 2PE implementations in noninvasive optical bioscopy or laser-based treatments point out to the relevance in clinical applications. Here we report about some basic aspects related to the phenomenon, implications in three-dimensional imaging microscopy, practical aspects related to design and realization of MPE microscopes, and we only give a list of potential applications and variations on the theme in order to offer a starting point for advancing new applications and developments. PMID:16756664

Diaspro, Alberto; Bianchini, Paolo; Vicidomini, Giuseppe; Faretta, Mario; Ramoino, Paola; Usai, Cesare

2006-01-01

97

Multi-photon excitation microscopy.  

PubMed

Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase their impact in areas such biotechnology, neurobiology, embryology, tissue engineering, materials science where imaging can be coupled to the possibility of using the microscopes in an active way, too. As well, 2PE implementations in noninvasive optical bioscopy or laser-based treatments point out to the relevance in clinical applications. Here we report about some basic aspects related to the phenomenon, implications in three-dimensional imaging microscopy, practical aspects related to design and realization of MPE microscopes, and we only give a list of potential applications and variations on the theme in order to offer a starting point for advancing new applications and developments. PMID:16756664

Diaspro, Alberto; Bianchini, Paolo; Vicidomini, Giuseppe; Faretta, Mario; Ramoino, Paola; Usai, Cesare

2006-01-01

98

Variable neutron star free precession in Hercules X-1 from evolution of RXTE X-ray pulse profiles with phase of the 35-d cycle  

NASA Astrophysics Data System (ADS)

Accretion of matter on to the surface of a freely precessing neutron star (NS) with a complex non-dipole magnetic field can explain the change of X-ray pulse profiles of Her X-1 observed by RXTE with the phase of the 35-d cycle. We demonstrate this using all available measurements of X-ray pulse profiles in the 9-13 keV energy range obtained with the RXTE/Proportional Counter Array (PCA). The measured profiles guided the elaboration of a geometrical model and the definition of locations of emitting poles, arcs and spots on the NS surface which satisfactorily reproduce the observed pulse profiles and their dependence on free precession phase. We have found that the observed trend of the times of the 35-d turn-ons on the O-C diagram, which can be approximated by a collection of consecutive linear segments around the mean value, can be described by our model by assuming a variable free precession period, with a fractional period change of about a few per cent. Under this assumption and using our model, we have found that the times of phase zero of the NS free precession (which we identify with the maximum separation of the brightest spot on the NS surface with the NS spin axis) occur about 1.6 d after the mean turn-on times inside each `stable' epoch, producing a linear trend on the O-C diagram with the same slope as the observed times of turn-ons. We propose that the 2.5 per cent changes in the free precession period that occur on time scales of several to tens of 35-d cycles can be related to wandering of the principal inertia axis of the NS body due to variations in the patterns of accretion on to the NS surface. The closeness of periods of the disc precession and the NS free precession can be explained by the presence of a synchronization mechanism in the system, which modulates the dynamical interaction of the gas streams and the accretion disc with the NS free precession period.

Postnov, K.; Shakura, N.; Staubert, R.; Kochetkova, A.; Klochkov, D.; Wilms, J.

2013-10-01

99

The Astrophysics Science Division Annual Report 2008  

NASA Technical Reports Server (NTRS)

The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum from gamma rays to radio wavelengths as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. This report includes the Division's activities during 2008.

Oegerle, William; Reddy, Francis; Tyler, Pat

2009-01-01

100

The Fall and the Rise of X-Rays from Dwarf Novae in Outburst: RXTE Observations of VW Hydri and WW Ceti  

NASA Technical Reports Server (NTRS)

In a dwarf nova, the accretion disk around the white dwarf is a source of ultraviolet, optical, and infrared photons, but is never hot enough to emit X-rays. Observed X-rays instead originate from the boundary layer between the disk and the white dwarf. As the disk switches between quiescence and outburst states, the 2-10 keV X-ray flux is usually seen to be anti-correlated with the optical brightness. Here we present RXTE monitoring observations of two dwarf novae, VW Hyi and WW Cet, confirming the optical/X-ray anti-correlation in these two systems. However, we do not detect any episodes of increased hard X-ray flux on the rise (out of two possible chances for WW Cet) or the decline (two for WW Cet and one for VW Hyi) from outburst, attributes that are clearly established in SS Cyg. The addition of these data to the existing literature establishes the fact that the behavior of SS Cyg is the exception, rather than the archetype as is often assumed. We speculate that only dwarf novae with a massive white dwarf may show these hard X-ray spikes.

Fertig, D.; Mukai, K.; Nelson, T.; Cannizzo, J. K.

2011-01-01

101

SIMULTANEOUS OBSERVATIONS OF PKS 2155-304 WITH HESS, FERMI, RXTE, AND ATOM: SPECTRAL ENERGY DISTRIBUTIONS AND VARIABILITY IN A LOW STATE  

SciTech Connect

We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of {gamma}-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; >100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little ({approx}30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155-304.

Aharonian, F.; Bernloehr, K.; Bochow, A.; Buehler, R. [Max-Planck-Institut fuer Kernphysik, P.O. Box 103980, D-69029 Heidelberg (Germany); Akhperjanian, A. G. [Yerevan Physics Institute, 2 Alikhanian Brothers Street, 375036 Yerevan (Armenia); Anton, G.; Brucker, J. [Universitaet Erlangen-Nuernberg, Physikalisches Institut, Erwin-Rommel-Str. 1, D-91058 Erlangen (Germany); Barres de Almeida, U.; Chadwick, P. M. [University of Durham, Department of Physics, South Road, Durham DH1 3LE (United Kingdom); Bazer-Bachi, A. R.; Borrel, V. [Centre d'Etude Spatiale des Rayonnements, CNRS/UPS, BP 44346, F-31028 Toulouse Cedex 4 (France); Becherini, Y. [Astroparticule et Cosmologie (APC), CNRS, Universite Paris 7 Denis Diderot, 10, rue Alice Domon et Leonie Duquet, F-75205 Paris Cedex 13 (France); Behera, B. [Landessternwarte, Universitaet Heidelberg, Koenigstuhl, D-69117 Heidelberg (Germany); Boisson, C. [LUTH, Observatoire de Paris, CNRS, Universite Paris Diderot, 5 Place Jules Janssen, 92190 Meudon (France); Brion, E.; Brun, P. [IRFU/DSM/CEA, CE Saclay, F-91191 Gif-sur-Yvette, Cedex (France); Bulik, T. [Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warsaw (Poland); Buesching, I. [Unit for Space Physics, Northwest University, Potchefstroom 2520 (South Africa); Boutelier, T. [Laboratoire d'Astrophysique de Grenoble, INSU/CNRS, Universite Joseph Fourier, BP 53, F-38041 Grenoble Cedex 9 (France); Charbonnier, A. [LPNHE, Universite Pierre et Marie Curie Paris 6, Universite Denis Diderot Paris 7, CNRS/IN2P3, 4 Place Jussieu, F-75252, Paris Cedex 5 (France)], E-mail: lucie.gerard@apc.univ-paris7.fr, E-mail: berrie@in2p3.fr, E-mail: sanchez@poly.in2p3.fr, E-mail: jchiang@slac.stanford.edu (and others)

2009-05-10

102

Simultaneous Observations of PKS 2155--304 with H.E.S.S., Fermi, RXTE and ATOM: Spectral Energy Distributions and Variability in a Low State  

SciTech Connect

We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of {gamma}-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; >100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little ({approx}30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155-304.

Aharonian, F.; /Heidelberg, Max Planck Inst. /Dublin Inst.; Akhperjanian, A.G.; /Yerevan Phys. Inst.; Anton, G.; /Erlangen - Nuremberg U.; Barres de Almeida, U.; /Durham U.; Bazer-Bachi, A.R.; /Toulouse, CESR; Becherini, Y.; /APC, Paris; Behera, B.; /Heidelberg Observ.; Bernlohr, K.; /Heidelberg, Max Planck Inst. /Humboldt U., Berlin; Boisson, C.; /LUTH, Meudon; Bochow, A.; /Heidelberg, Max Planck Inst.; Borrel, V.; /Toulouse, CESR; Brion, E.; /DAPNIA, Saclay; Brucker, J.; /Erlangen - Nuremberg U.; Brun, P.; /DAPNIA, Saclay; Buhler, R.; /Heidelberg, Max Planck Inst.; Bulik, T.; /Warsaw, Copernicus Astron. Ctr.; Busching, I.; /Western Ontario U.; Boutelier, T.; /Grenoble Observ.; Chadwick, P.M.; /Durham U.; Charbonnier, A.; /Paris U., VI-VII; Chaves, R.C.G.; /Heidelberg, Max Planck Inst. /Durham U. /Ecole Polytechnique /Heidelberg, Max Planck Inst. /Annecy, LAPP /Humboldt U., Berlin /Durham U. /Namibia U. /Western Ontario U. /Ecole Polytechnique /Heidelberg, Max Planck Inst. /Durham U. /APC, Paris /Heidelberg, Max Planck Inst. /Dublin Inst. /Annecy, LAPP /Grenoble Observ. /Warsaw, Copernicus Astron. Ctr. /Cracow, INP /Heidelberg, Max Planck Inst. /Heidelberg Observ. /APC, Paris /Montpellier U. /Montpellier U. /Montpellier U. /Heidelberg, Max Planck Inst. /Ecole Polytechnique /Humboldt U., Berlin /Dublin Inst. /Montpellier U. /APC, Paris /SLAC; /more authors..

2009-05-07

103

Analysis and Interpretation of Hard X-ray Emission fromthe Bullet Cluster (1E0657-56), the Most Distant Cluster of Galaxies Observed by the RXTE  

SciTech Connect

Evidence for non-thermal activity in clusters of galaxies is well established from radio observations of synchrotron emission by relativistic electrons. New windows in the Extreme Ultraviolet and Hard X-ray ranges have provided for more powerful tools for the investigation of this phenomenon. Detection of hard X-rays in the 20 to 100 keV range have been reported from several clusters of galaxies, notably from Coma and others. Based on these earlier observations we identified the relatively high redshift cluster 1E0657-56 (also known as RX J0658-5557) as a good candidate for hard X-ray observations. This cluster, also known as the bullet cluster, has many other interesting and unusual features, most notably that it is undergoing a merger, clearly visible in the X-ray images. Here we present results from a successful RXTE observations of this cluster. We summarize past observations and their theoretical interpretation which guided us in the selection process. We describe the new observations and present the constraints we can set on the flux and spectrum of the hard X-rays. Finally we discuss the constraints one can set on the characteristics of accelerated electrons which produce the hard X-rays and the radio radiation.

Petrosian, Vahe; /Stanford U., Phys. Dept. /SLAC /Stanford U., Appl. Phys. Dept.; Madejski, Greg; /SLAC; Luli, Kevin; /Stanford U., Phys. Dept.

2006-08-16

104

Simultaneous Observations of PKS 2155-304 with HESS, Fermi, RXTE, and Atom: Spectral Energy Distributions and Variability in a Low State  

NASA Astrophysics Data System (ADS)

We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of ?-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; >100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little (~30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155-304.

Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Barres de Almeida, U.; Bazer-Bachi, A. R.; Becherini, Y.; Behera, B.; Bernlöhr, K.; Boisson, C.; Bochow, A.; Borrel, V.; Brion, E.; Brucker, J.; Brun, P.; Bühler, R.; Bulik, T.; Büsching, I.; Boutelier, T.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Chounet, L.-M.; Clapson, A. C.; Coignet, G.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; O'C. Drury, L.; Dubois, F.; Dubus, G.; Dyks, J.; Dyrda, M.; Egberts, K.; Emmanoulopoulos, D.; Espigat, P.; Farnier, C.; Feinstein, F.; Fiasson, A.; Förster, A.; Fontaine, G.; Füßling, M.; Gabici, S.; Gallant, Y. A.; Gérard, L.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Goret, P.; Göhring, D.; Hauser, D.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Holleran, M.; Hoppe, S.; Horns, D.; Jacholkowska, A.; de Jager, O. C.; Jahn, C.; Jung, I.; Katarzy?ski, K.; Katz, U.; Kaufmann, S.; Kendziorra, E.; Kerschhaggl, M.; Khangulyan, D.; Khélifi, B.; Keogh, D.; Klu?niak, W.; Komin, Nu.; Kosack, K.; Lamanna, G.; Lenain, J.-P.; Lohse, T.; Marandon, V.; Martin, J. M.; Martineau-Huynh, O.; Marcowith, A.; Maurin, D.; McComb, T. J. L.; Medina, M. C.; Moderski, R.; Moulin, E.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Niemiec, J.; Nolan, S. J.; Ohm, S.; Olive, J.-F.; de Oña Wilhelmi, E.; Orford, K. J.; Ostrowski, M.; Panter, M.; Arribas, M. Paz; Pedaletti, G.; Pelletier, G.; Petrucci, P.-O.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raubenheimer, B. C.; Raue, M.; Rayner, S. M.; Renaud, M.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Ruppel, J.; Sahakian, V.; Santangelo, A.; Schlickeiser, R.; Schöck, F. M.; Schröder, R.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Shalchi, A.; Sikora, M.; Skilton, J. L.; Sol, H.; Spangler, D.; Stawarz, ?.; Steenkamp, R.; Stegmann, C.; Superina, G.; Szostek, A.; Tam, P. H.; Tavernet, J.-P.; Terrier, R.; Tibolla, O.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Venter, L.; Vialle, J. P.; Vincent, P.; Vivier, M.; Völk, H. J.; Volpe, F.; Wagner, S. J.; Ward, M.; Zdziarski, A. A.; Zech, A.; H.E.S.S. Collaboration; Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Battelino, M.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chen, A. W.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Colafrancesco, S.; Conrad, J.; Costamante, L.; Cutini, S.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Digel, S. W.; do Couto e Silva, E.; Drell, P. S.; Dubois, R.; Dubus, G.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Fleury, P.; Focke, W. B.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giordano, F.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Horan, D.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, W. N.; Kadler, M.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kerr, M.; Knödlseder, J.; Kuehn, F.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Madejski, G. M.; Makeev, A.; Mazziotta, M. N.; McEnery, J. E.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rodriguez, A. Y.; Ryde, F.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Scargle, J. D.; Schalk, T. L.; Sellerholm, A.; Sgrò, C.; Shaw, M.; Smith, D. A.; Spandre, G.; Spinelli, P.; Starck, J.-L.; Strickman, M. S.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vilchez, N.; Villata, M.; Vitale, V.; Waite, A. P.; Wood, K. S.; Ylinen, T.; Ziegler, M.; Fermi LAT Collaboration

2009-05-01

105

RXTE Observations of the Low-Mass X-Ray Binary 4U 1608-522 in Upper-Banana State  

E-print Network

To investigate the physics of mass accretion onto weakly-magnetized neutron stars, 95 archival RXTE datasets of an atoll source 4U 1608-522, acquired over 1996-2004 in so-called upper-banana state, were analyzed. The object meantime exhibited 3-30 keV luminosity in the range of <~ 10^35 - 4 x 10^37 erg s^-1, assuming a distance of 3.6 kpc. The 3-30 keV PCA spectra, produced one from each dataset, were represented successfully with a combination of a soft and a hard component, of which the presence was revealed in a model-independent manner by studying spectral variations among the observations. The soft component is expressed by so-called multi-color disk model with a temperature of ~1.8 keV, and is attributed to the emission from an optically-thick standard accretion disk. The hard component is a blackbody emission with a temperature of ~2.7 keV, thought to be emitted from the neutron-star surface. As the total luminosity increases, a continuous decrease was observed in the ratio of the blackbody luminosi...

Takahashi, Hiromitsu; Makishima, Kazuo

2011-01-01

106

Magnetostrictive resonance excitation  

DOEpatents

The resonance frequency spectrum of a magnetostrictive sample is remotely determined by exciting the magnetostrictive property with an oscillating magnetic field. The permeability of a magnetostrictive material and concomitant coupling with a detection coil varies with the strain in the material whereby resonance responses of the sample can be readily detected. A suitable sample may be a magnetostrictive material or some other material having at least one side coated with a magnetostrictive material. When the sample is a suitable shape, i.e., a cube, rectangular parallelepiped, solid sphere or spherical shell, the elastic moduli or the material can be analytically determined from the measured resonance frequency spectrum. No mechanical transducers are required and the sample excitation is obtained without contact with the sample, leading to highly reproducible results and a measurement capability over a wide temperature range, e.g. from liquid nitrogen temperature to the Curie temperature of the magnetostrictive material.

Schwarz, Ricardo B. (Los Alamos, NM); Kuokkala, Veli-Tapani (Tampere, FI)

1992-01-01

107

Capturing Excitement: Oceanography  

ERIC Educational Resources Information Center

Describes four elementary school earth science activities. Each student experience is designed to help children answer questions about the ocean floor, continental drift, volcanism and mountain chains. Includes a bibliography of related articles, books, and maps. (JM)

Boyer, Robert E.; Butts, David P.

1971-01-01

108

Temperature and excitable cells  

PubMed Central

Temperature affects a host of biological processes, one of which is the conduction velocity of action potentials (AP). The velocity-temperature profile of APs has remained remarkably conserved across excitable animal and plant cells. Herein, we will not analyze this behavior in terms of temperature sensitivities of single molecules (e.g., ion channels), but rather we present a phenomenological thermodynamic interpretation. By assuming that APs are acoustic phenomena, one arrives at testable predictions about the temperature-dependence of the macroscopic material properties of the excitable cell membrane. These material properties set constraints on the excitability of a cell membrane and allow us to hypothesize about its typical relaxation timescales. The presented approach—by virtue of its thermodynamic nature—is by no means limited to temperature. It applies equally well to all thermodynamic variables (e.g., mechanical stretch, pH, ion concentrations, etc.) and to underline this argument we discuss some implications and predictions for sensory physiology. PMID:24563710

Fillafer, Christian; Schneider, Matthias F

2013-01-01

109

Pulse excitation of bolometer bridges  

NASA Technical Reports Server (NTRS)

Driving bolometer bridge by appropriately phased excitation pulses increases signal-to-noise ratio of bolometer sensor which operates on a chopped light beam. Method allows higher applied voltage than is possible by conventional ac or dc excitation.

Rusk, S. J.

1972-01-01

110

Apparatus for photon excited catalysis  

NASA Technical Reports Server (NTRS)

An apparatus is described for increasing the yield of photonically excited gas phase reactions by extracting excess energy from unstable, excited species by contacting the species with the surface of a finely divided solid.

Saffren, M. M. (inventor)

1977-01-01

111

Science Career Magazine.  

ERIC Educational Resources Information Center

This magazine is designed for teachers and students in junior and senior high schools. It is intended to help students become more aware about what scientists and engineers do, what's new and exciting in the fields of science and engineering, and what satisfactions might be expected from a career in one of the many different areas of science and…

Halsey, Linda B., Ed.; Sweeley, Charles C., Ed.

112

Behavioural Science for  

E-print Network

and scientific activities of staff from Stirling's Behavioural Science Centre. This exciting course teaches at Stirling? One The Course has been developed in consultation with the Behavioural Science Centre at Stirling environment and the links with Industry and Policy groups being developed by Stirling Management School

Little, Tony

113

Bitten by the Science "Bug"  

NSDL National Science Digital Library

Who would have thought that a primary level science camp would spark exciting science programs for the more than 1,000 elementary students in one school district in Stephenville, Texas? This article details the development of a science camp for kindergarten through second-grade students. This popular program began with one teacher's vision of strengthening students' science-process skills and teaching science inquiry at her school and eventually spread throughout the school district.

Viki Hymer

2005-07-01

114

Expanding Science Knowledge: Enabled by Nuclear Power  

NASA Technical Reports Server (NTRS)

The availability of Radioisotope Power Sources (RPSs) power opens up new and exciting mission concepts (1) New trajectories available (2) Power for long term science and operations Astonishing science value associated with these previously non-viable missions

Clark, Karla B.

2011-01-01

115

Who Am I? ASE Science Year Resources: Bringing Science Year into the Classroom. [CD-ROM].  

ERIC Educational Resources Information Center

This CD-ROM describes how science can be used in schools to show that students can be excited and engaged in science and how science can be integrated into other disciplines. Science Year is a 12-month packed calendar of events, projects and resources, designed to stimulate the imagination about science and technology. Activities include the…

Association for Science Education, Herts (England).

116

RXTE Monitoring of the Anomalous X-ray Pulsar 1E 1048.1-5937: Long-Term Variability and the 2007 March Event  

NASA Technical Reports Server (NTRS)

After three years of no unusual activity, Anomalous X-ray Pulsar 1E 1048.1-5937 reactivated in 2007 March. We report on the detection of a large glitch (deltav/v = 1.63(2) x 10(exp -5)) on 2007 March 26 (MJD 54185.9), contemporaneous with the onset of a pulsed-flux flare, the third flare observed from this source in 10 years of monitoring with the Rossi X-ray Timing Explorer. Additionally, we report on a detailed study of the evolution of the timing properties, the pulsed flux, and the pulse profile of this source as measured by RXTE from 1996 July to 2008 January. In our timing study, we attempted phase coherent timing of all available observations. We show that in 2001, a timing anomaly of uncertain nature occurred near the rise of the first pulsed flux flare; we show that a likely glitch (deltav/v = 2.91(9) x 10(exp -6)) occurred in 2002, near the rise of the second flare, and we present a detailed description of the variations in the spin-down. In our pulsed flux study, we compare the decays of the three flares and discuss changes in the hardness ratio. In our pulse profile study, we show that the profile exhibited large variations near the peak of the first two flares, and several small short-term profile variations during the most recent flare. Finally, we report on the discovery of a small burst 27 days after the peak of the last flare, the fourth burst discovered from this source. We discuss the relationships between the observed properties in the framework of the magnetar model.

Dib, Rim; Kaspi, Victoria M.; Gavriil, Fotis P.

2009-01-01

117

RXTE Measurement of the Diffuse X-ray Emission From the Galactic Ridge: Implications for the Energetics of the Interstellar Medium  

E-print Network

(Abridged) The diffuse X-ray emission from the thin disk surrounding the Galactic mid-plane (the so-called Galactic ridge) was measured with RXTE PCA in order to determine the spatial extent, spectral nature, and origin of the emission. Spatial examination of the diffuse emission in the central 30 deg of the plane in Galactic longitude reveals the presence of two components: a thin disk of full width less than 0.5 deg centered roughly on the Galactic mid-plane, and a broad component which can be approximated as a Gaussian distribution with FWHM of about 4 deg. Spectral examination of the emission clearly reveals the presence of a hard power law tail above 10 keV and an emission line from He-like iron, indicating both thermal and possibly non-thermal origins for the diffuse emission. The averaged spectrum from the ridge in the 3-35 keV band can be modelled with a Raymond-Smith plasma component of temperature ~2-3 keV and a power law component of photon index ~1.8. Based on this finding, we argue that the temperature of the hot phase of the Interstellar Medium (ISM) is less than the previously reported values of 5-15 keV. We find that a SN explosion rate of less than 5 per century is adequate to power the thermal emission from the ridge. We speculate that bremsstrahlung of accelerated electrons and protons in SNR sites can play a significant role in producing the hard tail of the spectrum. Moreover, their collisional losses can play a major role in the ionization of the ISM.

Azita Valinia; Francis E. Marshall

1998-04-01

118

RXTE Observations of Anomalous X-ray Pulsar 1E 1547.0-5408 During and After its 2008 and 2009 Outbursts  

NASA Technical Reports Server (NTRS)

We present the results of Rossi X-ray Timing Explorer (RXTE) and Swift monitoring observations of the magnetar 1E 1547.0-5408 following the pulsar's radiative outbursts in 2008 October and 2009 January. We report on a study of the evolution of the timing properties and the pulsed flux from 2008 October 4 through 2009 December 26. In our timing study, a phase-coherent analysis shows that for the first 29 days following the 2008 outburst, there was a very fast increase in the magnitude of the rotational frequency derivative upsilon-dot, such that upsilon-dot-dot was a factor of 60 larger than that reported in data from 2007. This upsilon-dot magnitude increase occurred in concert with the decay of the pulsed flux following the start of the 2008 event. Following the 2009 outburst, for the first 23 days, upsilon-dot-dot was consistent with zero, and upsilon-dot had returned to close to its 2007 value. In contrast to the 2008 event, the 2009 outburst showed a major increase in persistent flux, relatively little change in the pulsed flux, and sudden significant spectral hardening approx 15 days after the outburst. We show that, excluding the month following each of the outbursts, and because of the noise and the sparsity in the data, multiple plausible timing solutions fit the pulsar's frequency behavior. We note similarities in the behavior of 1E 1547.0-5408 following the 2008 outburst to that seen in the AXP 1E 1048.1-5937 following its 2001-2002 outburst and discuss this in terms of the magnetar model.

Dib, Rim; Kaspi, Victoria M.; Scholz, Paul; Gavriil, Fotis P.

2012-01-01

119

First simultaneous multi-wavelength observations of the black hole candidate IGR J17091-3624. ATCA, INTEGRAL, Swift, and RXTE views of the 2011 outburst  

NASA Astrophysics Data System (ADS)

We present the results of the first four (quasi-)simultaneous radio (ATCA), X-ray (Swift, RXTE), and ?-ray (INTEGRAL) observations of the black hole candidate IGR J17091-3624, performed in February and March 2011. The X-ray analysis shows that the source was in the hard state, and then it transited to a soft intermediate state. We study the correlated radio/X-ray behaviour of this source for the first time. The radio counterpart to IGR J17091-3624 was detected during all four observations with the ATCA. In the hard state, the radio spectrum is typical of optically thick synchrotron emission from a self-absorbed compact jet. In the soft intermediate state, the detection of optically thin synchrotron emission is probably due to a discrete ejection event associated with the state transition. The position of IGR J17091-3624 in the radio versus X-ray luminosity diagram (aka fundamental plane) is compatible with that of the other black hole sources for distances greater than 11 kpc. IGR J17091-3624 also appears as a new member of the few sources that show a strong quenching of radio emission after the state transition. Using the estimated luminosity at the spectral transition from the hard state, and for a typical mass of 10 M?, we estimate a distance to the source between ~11 and ~17 kpc, compatible with the radio behaviour of the source. Table 4 is available in electronic form at http://www.aanda.org

Rodriguez, J.; Corbel, S.; Caballero, I.; Tomsick, J. A.; Tzioumis, T.; Paizis, A.; Cadolle Bel, M.; Kuulkers, E.

2011-09-01

120

Self-excitation of single nanomechanical pillars  

NASA Astrophysics Data System (ADS)

Self-excitation is a mechanism that is ubiquitous for electromechanical power devices such as electrical generators. This is conventionally achieved by making use of the magnetic field component in electrical generators (Nedic and Lipo 2000 IEEE/IAS Conf. Records (Rome, Italy) vol 1 pp 51-6), a good and widely visible example of which is the wind turbine farm (Muljadi et al 2005 J. Sol. Energy Eng. 127 581-7). In other words, a static force, such as the wind acting on rotor blades, can generate a resonant excitation at a certain mechanical frequency. For nanomechanical systems (Craighead 2000 Science 290 1532-5 Roukes 2001 Phys. World 14 25-31 Cleland 2003 Foundations of Nanomechanics (Berlin: Springer); Ayari et al 2007 Nano Lett. 7 2252-7 Koenig et al 2008 Nat. Nanotechnol. 3 482-4) such a self-excitation (SE) mechanism is also highly desirable, because it can generate mechanical oscillations at radio frequencies by simply applying a dc bias voltage. This is of great importance for low-power signal communication devices and detectors, as well as for mechanical computing elements. For a particular nanomechanical system—the single electron shuttle—this effect was predicted some time ago by Gorelik et al (Phys. Rev. Lett. 80 4526-9). Here, we use a nanoelectromechanical single electron transistor (NEMSET) to demonstrate self-excitation for both the soft and hard regimes, respectively. The ability to use self-excitation in nanomechanical systems may enable the detection of quantum mechanical backaction effects (Naik et al 2006 Nature 443 193-6) in direct tunneling, macroscopic quantum tunneling (Savelev et al 2006 New J. Phys. 8 105-15) and rectification (Pistolesi and Fazio 2005 Phys. Rev. Lett. 94 036806-4). All these effects have so far been overshadowed by the large driving voltages that had to be applied.

Kim, Hyun S.; Qin, Hua; Blick, Robert H.

2010-03-01

121

Science Sampler: Growth Potential  

NSDL National Science Digital Library

Students will enjoy carrying out this exciting and challenging research project that combines science with computers and mathematics to investigate how polyacrylate animals change in size over time when placed in water and aqueous salt solutions. The hands-on activity motivates students and provides them with enjoyable and rewarding science project experiences. Here they have an opportunity to solve a problem and use the science inquiry skills of observing, collecting, organizing, and analyzing data.

Dana M. Barry

2004-04-01

122

Excitability in Dictyostelium development  

NASA Astrophysics Data System (ADS)

Discovering how populations of cells reliably develop into complex multi-cellular structures is a key challenge in modern developmental biology. This requires an understanding of how networks at the single-cell level, when combined with intercellular signaling and environmental cues, give rise to the collective behaviors observed in cellular populations. I will present work in collaboration with the Gregor lab, showing that the signal-relay response of starved cells of the amoebae Dictyostelium discoideum can be well modeled as an excitable system. This is in contrast to existing models of the network that postulate a feed-forward cascade. I then extend the signal-relay model to describe how spatial gradient sensing may be achieved via excitability. One potential advantage of relying on feedback for gradient sensing is in preventing ``cheaters'' that do not produce signals from taking over the population. I then combine these models of single-cell signaling and chemotaxis to perform large-scale agent-based simulations of aggregating populations. This allows direct study of how variations in single-cell dynamics modify population behavior. In order to further test this model, I use the results of a screen for mutant cell lines that exhibit altered collective patterns. Finally, I use an existing FRET movie database of starved cell populations at varying cell densities and dilution rates to study heterogeneity in repeated spatio-temporal activity patterns.

Schwab, David

2013-03-01

123

Neutron Scattering Studies of spin excitations in hole-doped  

E-print Network

Neutron Scattering Studies of spin excitations in hole-doped Ba0.67K0.33Fe2As2 superconductor Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA, 4 University, West Lafayette, Indiana 47907, USA. We report inelastic neutron scattering experiments on single

Wang, Wei Hua

124

The Balloons Go Up for Science.  

ERIC Educational Resources Information Center

Describes the planning and implementation of a science week intended to raise the awareness of science in an elementary school. Educational requirements included exciting science happenings and concentrated science teaching of a high standard. The week included demonstrations, guest speakers, and schoolwide assemblies. Demonstrations included the…

Fayle, Maureen

1998-01-01

125

Fusion excitation function revisited  

E-print Network

We report on a comprehensive systematics of fusion-evaporation and/or fusion-fission cross sections for a very large variety of systems over an energy range 4-155 A.MeV. Scaled by the reaction cross sections, fusion cross sections do not show a universal behavior valid for all systems although a high degree of correlation is present when data are ordered by the system mass asymmetry.For the rather light and close to mass-symmetric systems the main characteristics of the complete and incomplete fusion excitation functions can be precisely determined. Despite an evident lack of data above 15A.MeV for all heavy systems the available data suggests that geometrical effects could explain the persistence of incomplete fusion at incident energies as high as 155A.MeV.

Ph. Eudes; Z. Basrak; F. Sébille; V. de la Mota; G. Royer; M. Zori?

2012-09-28

126

STUDIES OF EXCITABLE MEMBRANES  

PubMed Central

The neuromuscular junctions and nonjunctional sarcolemmas of mammalian skeletal muscle fibers were studied by conventional thin-section electron microscopy and freeze-fracture techniques. A modified acetylcholinesterase staining procedure that is compatible with light microscopy, conventional thin-section electron microscopy, and freeze-fracture techniques is described. Freeze-fracture replicas were utilized to visualize the internal macromolecular architecture of the nerve terminal membrane, the chemically excitable neuromuscular junction postsynaptic folds, and the electrically excitable nonjunctional sarcolemma. The nerve terminal membrane is characterized by two parallel rows of 100–110-Å particles which may be associated with synpatic vesicle fusion and release. On the postsynpatic folds, irregular rows of densely packed 110–140-Å particles were observed and evidence is assembled which indicates that these large transmembrane macromolecules may represent the morphological correlate for functional acetylcholine receptor activity in mammalian motor endplates. Differences in the size and distribution of particles in mammalian as compared with amphibian and fish postsynaptic junctional membranes are correlated with current biochemical and electron micrograph autoradiographic data. Orthogonal arrays of 60-Å particles were observed in the split postsynaptic sarcolemmas of many diaphragm myofibers. On the basis of differences in the number and distribution of these "square" arrays within the sarcolemmas, two classes of fibers were identified in the diaphragm. Subsequent confirmation of the fiber types as fast- and slow-twitch fibers (Ellisman et al. 1974. J. Cell Biol. 63[2, Pt. 2]:93 a. [Abstr.]) may indicate a possible role for the square arrays in the electrogenic mechanism. Experiments in progress involving specific labeling techniques are expected to permit positive identification of many of these intriguing transmembrane macromolecules. PMID:4138515

Rash, John E.; Ellisman, Mark H.

1974-01-01

127

Follow-Up with Students after 6 Years of Participation in Project Excite  

ERIC Educational Resources Information Center

Project EXCITE is a program for minority students that supplements the regular school offerings with an emphasis on enhancing students' interest and performance in math and science. This study examines the experience and perceptions of 14 student participants in the program and their parents. In student and parent interviews, Project EXCITE was…

Lee, Seon-Young; Olszewski-Kubilius, Paula; Peternel, George

2009-01-01

128

Optically excited states in positronium  

NASA Technical Reports Server (NTRS)

Optical excitation are reported of the 1 3S-2 3P transition in positronium, and a second excitation from n=2 to higher n states. The experiment used light from two pulsed dye lasers. Changes in the positronium annihilation rate during and after the laser pulse were used to deduce the excited state populations. The n=2 level was found to be saturable and excitable to a substantial fraction of n=2 positronium to higher levels. Preliminary spectroscopic measurements were performed on n=14 and n=15 positronium.

Howell, R. H.; Ziock, Klaus P.; Magnotta, F.; Dermer, Charles D.; Failor, R. A.; Jones, K. M.

1990-01-01

129

The accretion flow to the intermittent accreting millisecond pulsar, HETE J1900.1-2455, as observed by XMM-Newton and RXTE  

NASA Astrophysics Data System (ADS)

We present a study of the accretion flow to the intermittent accreting millisecond pulsar, HETE J1900.1-2455, based on observations made simultaneously by XMM-Newton and RXTE. The 0.33-50 keV energy spectrum is described by the sum of a hard Comptonized component produced in an optically thin ? ? 1 corona, a soft thermal kTin ? 0.2 keV component interpreted as accretion disc emission, and of disc reflection of the hard component. Two emission features are detected at energies of 0.98(1) and 6.58(7) keV, respectively. The latter is identified as K? transition of Fe XXIII-XXV. A simultaneous detection in the European Photon Imaging Camera (EPIC-pn), EPIC-MOS2 and Reflection Grating Spectrometer (RGS) spectra favours an astrophysical origin also for the latter, which has an energy compatible with Fe-L? and helium-like Ne-K? transitions. The broadness of the two features, ?/E ? 0.1, suggests a common origin, resulting from reflection in an accretion disc with inclination of (30+ 4- 3)°, and extending down to Rin = 25+ 16- 11 gravitational radii from the compact object. However, the strength of the feature at lower energy measured by EPIC-pn cannot be entirely reconciled with the amplitude of the Fe-K? line, hampering the possibility of describing it in terms of a broad-band reflection model, and preventing a firm identification. Pulsations at the known 377.3 Hz spin frequency could not be detected with an upper limit of 0.4 per cent at 3? confidence level on the pulsed fractional amplitude. We interpret the value of the inner disc radius estimated from spectral modelling and the lack of significant detection of coherent X-ray pulsations as an indication of a disc accretion flow truncated by some mechanism connected to the overall evolution of the accretion disc, rather than by the neutron star magnetic field. This is compatible with the extremely close similarity of spectral and temporal properties of this source with respect to other, non-pulsing atoll sources in the hard state.

Papitto, A.; D'Aì, A.; Di Salvo, T.; Egron, E.; Bozzo, E.; Burderi, L.; Iaria, R.; Riggio, A.; Menna, M. T.

2013-03-01

130

Science Outreach Science Outreach  

E-print Network

program. Volunteers can help your school with science fair projects and conducting science activitiesScience Outreach Science Outreach AT SFU'S FACULTY OF SCIENCE OUR PASSION IS SCIENCE EDUCATION At SFU's Faculty of Science our passion is science education #12;coming sooncoming soon The Trottier

131

A Comparison of the Variability of the Symbiotic X-ray Binaries GX 1+4, 4U 1954+31, and 4U 1700+24 from Swift/BAT and RXTE/ASM Observations  

NASA Technical Reports Server (NTRS)

We present an analysis of the X-ray variability of three symbiotic X-ray binaries, GX 1+4, 4U 1700+24, and 4U 1954+31, using observations made with the Swift Burst Alert Telescope (BAT) and the Rossi X-ray Timing Explorer (RXTE) All-Sky Monitor (ASM). Observations of 4U 1954+31 with the Swift BAT show modulation at a period near 5 hours. Models to explain this modulation are discussed including the presence of an exceptionally slow X-ray pulsar in the system and accretion instabilities. We conclude that the most likely interpretation is that 4U 1954+31 contains one of the slowest known X-ray pulsars. Unlike 4U 1954+31, neither GX 1+4 nor 4U 1700+24 show any evidence for modulation on a timescale of hours. An analysis of the RXTE ASM light curves of GX l+4, 4U 1700+24, and 4U 1954+31 does not show the presence of periodic modulation in any source, although there is considerable variability on long timescales for all three sources. There is no modulation in GX 1+4 on either the optical 1161 day orbital period or a previously reported 304 day X-ray period. For 4U 1700+24 we do not confirm the 404 day period previously proposed for this source from a shorter duration ASM light curve.

Corbet, R. H. D.; Sokoloski, J. L.; Mukai, K.; Markwardt, C. B.; Tueller, J.

2007-01-01

132

Attosecond Photoscopy of Plasmonic Excitations  

NASA Astrophysics Data System (ADS)

We propose an experimental arrangement to image, with attosecond resolution, transient surface plasmonic excitations. The required modifications to state-of-the-art setups used for attosecond streaking experiments from solid surfaces only involve available technology. Buildup and lifetimes of surface plasmon polaritons can be extracted and local modulations of the exciting optical pulse can be diagnosed in situ.

Lupetti, Mattia; Hengster, Julia; Uphues, Thorsten; Scrinzi, Armin

2014-09-01

133

Attosecond photoscopy of plasmonic excitations.  

PubMed

We propose an experimental arrangement to image, with attosecond resolution, transient surface plasmonic excitations. The required modifications to state-of-the-art setups used for attosecond streaking experiments from solid surfaces only involve available technology. Buildup and lifetimes of surface plasmon polaritons can be extracted and local modulations of the exciting optical pulse can be diagnosed in situ. PMID:25259981

Lupetti, Mattia; Hengster, Julia; Uphues, Thorsten; Scrinzi, Armin

2014-09-12

134

Excited waves in shear layers  

NASA Technical Reports Server (NTRS)

The generation of instability waves in free shear layers is investigated. The model assumes an infinitesimally thin shear layer shed from a semi-infinite plate which is exposed to sound excitation. The acoustical shear layer excitation by a source further away from the plate edge in the downstream direction is very weak while upstream from the plate edge the excitation is relatively efficient. A special solution is given for the source at the plate edge. The theory is then extended to two streams on both sides of the shear layer having different velocities and densities. Furthermore, the excitation of a shear layer in a channel is calculated. A reference quantity is found for the magnitude of the excited instability waves. For a comparison with measurements, numerical computations of the velocity field outside the shear layer were carried out.

Bechert, D. W.

1982-01-01

135

YES Mag: Science Projects  

NSDL National Science Digital Library

Parents, are you looking for a way to excite your children about science? This website developed by YES Mag, Canada's science magazine for kids, may just have the answer. Users can find numerous fun science activities addressing many of the basic science principles and phenomena including Newton's third law, lightening, wind, and chromatography. Each activity includes pictures to assist in the implementation of the project as well as a convenient printable version. With over thirty-five activities, children are sure to have a fun learning experience.

136

Discovery Channel: Science Fair Central  

NSDL National Science Digital Library

The Discovery Channel promotes student participation in science fairs at this appealing, vibrant website. Users can find a terrific, thorough guide to creating science fair projects, including project ideas and lists of books and external web sites for students to utilize during their research. Students can find tip sheets for projects in many science subjects including astronomy, chemistry, and earth science. Educators can discover how to organize a science fair and parents can learn how to get involved with their children's projects. This site is a great way to excite children about science and scientific investigations.

137

Radioactivity Induced by Nuclear Excitation I. Excitation by Neutrons  

Microsoft Academic Search

It is shown that the 4.1-hr. period of indium can be produced by nuclear excitation of indium and is to be attributed to an excited metastable state, In115,* of the stable In115. This result is obtained by studying the radioactivity produced in indium by neutrons of different energy distributions and by studying the chain reactions produced in cadmium by fast

M. Goldhaber; R. D. Hill; Leo Szilard

1939-01-01

138

Industrial applications of photonuclear resonance excitation  

E-print Network

Photonuclear resonance excitation refers to a variety of photonuclear interaction processes that lead to the excitation of a nucleus from some initial state to a higher energy nuclear state. Typical excited nuclear state ...

Chichester, David Lee, 1971-

2000-01-01

139

Faculty of Science Medical Physics  

E-print Network

Faculty of Science Medical Physics If you like physics and mathematics, but want a career in the rapidly expanding health sciences, then this honours BSc is for you. www.uwindsor.ca/physics Medical Physics opens the way to exciting new possibilities for career opportunities in the applications

140

Parametric Excitation of a DWSC  

E-print Network

methods of analysis and the effect of damping (especially viscous drag) on parametric excitation and instability. The thesis uses Mathieu's equation as the basis for stability analysis and time-simulates the coupled heave-sway-roll EOM. Time...

Lakhotia, Chandan

2011-08-08

141

Laser-induced nuclear excitation  

SciTech Connect

An analysis is presented of the Coulomb excitation of low-lying nuclear levels by the electrons produced by strong-field ionization of atoms. It is shown that the resulting short-lived radioactivity can be as high as on the order of 10{sup 3} Ci for certain isotopes excited by using modern laser systems. Relativistic effects are demonstrated that substantially increase radioactivity as compared to that predicted by nonrelativistic theory results.

Zon, B. A., E-mail: zon@niif.vsu.ru; Kornev, A. S., E-mail: a-kornev@yandex.r [Voronezh State University (Russian Federation)

2010-05-15

142

Redox Control of Cardiac Excitability  

PubMed Central

Abstract Reactive oxygen species (ROS) have been associated with various human diseases, and considerable attention has been paid to investigate their physiological effects. Various ROS are synthesized in the mitochondria and accumulate in the cytoplasm if the cellular antioxidant defense mechanism fails. The critical balance of this ROS synthesis and antioxidant defense systems is termed the redox system of the cell. Various cardiovascular diseases have also been affected by redox to different degrees. ROS have been indicated as both detrimental and protective, via different cellular pathways, for cardiac myocyte functions, electrophysiology, and pharmacology. Mostly, the ROS functions depend on the type and amount of ROS synthesized. While the literature clearly indicates ROS effects on cardiac contractility, their effects on cardiac excitability are relatively under appreciated. Cardiac excitability depends on the functions of various cardiac sarcolemal or mitochondrial ion channels carrying various depolarizing or repolarizing currents that also maintain cellular ionic homeostasis. ROS alter the functions of these ion channels to various degrees to determine excitability by affecting the cellular resting potential and the morphology of the cardiac action potential. Thus, redox balance regulates cardiac excitability, and under pathological regulation, may alter action potential propagation to cause arrhythmia. Understanding how redox affects cellular excitability may lead to potential prophylaxis or treatment for various arrhythmias. This review will focus on the studies of redox and cardiac excitation. Antioxid. Redox Signal. 18, 432–468. PMID:22897788

Aggarwal, Nitin T.

2013-01-01

143

Electron-excited molecule interactions  

SciTech Connect

In this paper the limited but significant knowledge to date on electron scattering from vibrationally/rotationally excited molecules and electron scattering from and electron impact ionization of electronically excited molecules is briefly summarized and discussed. The profound effects of the internal energy content of a molecule on its electron attachment properties are highlighted focusing in particular on electron attachment to vibrationally/rotationally and to electronically excited molecules. The limited knowledge to date on electron-excited molecule interactions clearly shows that the cross sections for certain electron-molecule collision processes can be very different from those involving ground state molecules. For example, optically enhanced electron attachment studies have shown that electron attachment to electronically excited molecules can occur with cross sections 10{sup 6} to 10{sup 7} times larger compared to ground state molecules. The study of electron-excited molecule interactions offers many experimental and theoretical challenges and opportunities and is both of fundamental and technological significance. 54 refs., 15 figs.

Christophorou, L.G. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA). Dept. of Physics)

1991-01-01

144

Electrostatic Tuning of Cellular Excitability  

PubMed Central

Abstract Voltage-gated ion channels regulate the electric activity of excitable tissues, such as the heart and brain. Therefore, treatment for conditions of disturbed excitability is often based on drugs that target ion channels. In this study of a voltage-gated K channel, we propose what we believe to be a novel pharmacological mechanism for how to regulate channel activity. Charged lipophilic substances can tune channel opening, and consequently excitability, by an electrostatic interaction with the channel's voltage sensors. The direction of the effect depends on the charge of the substance. This was shown by three compounds sharing an arachidonyl backbone but bearing different charge: arachidonic acid, methyl arachidonate, and arachidonyl amine. Computer simulations of membrane excitability showed that small changes in the voltage dependence of Na and K channels have prominent impact on excitability and the tendency for repetitive firing. For instance, a shift in the voltage dependence of a K channel with ?5 or +5 mV corresponds to a threefold increase or decrease in K channel density, respectively. We suggest that electrostatic tuning of ion channel activity constitutes a novel and powerful pharmacological approach with which to affect cellular excitability. PMID:20141752

Börjesson, Sara I.; Parkkari, Teija; Hammarström, Sven; Elinder, Fredrik

2010-01-01

145

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2013 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation. In general, excitation must meet...

2013-10-01

146

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2011 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation. In general, excitation must meet...

2011-10-01

147

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2012 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation. In general, excitation must meet...

2012-10-01

148

Science Shorts: More Than One Way to Investigate  

NSDL National Science Digital Library

An exciting element of science fairs is that they give students the opportunity to explore various interests through scientific investigation. Many students, however, mistakenly think that all investigations are experiments. This lesson can help broaden students' conceptions of science.

2007-12-01

149

Safer Science: Building Safety Into Construction or Renovations  

NSDL National Science Digital Library

Designing a new science laboratory or renovating an existing one can be an exciting experience. Though science teachers may have a better understanding of laboratory needs than most administrators, many schools tend to limit or exclude them from the plann

Ken Roy

2010-12-01

150

Science in Orbit  

NASA Technical Reports Server (NTRS)

This talk presents the excitement of doing science in space. It reviews some of the effects of the physical adaptations that the body undergoes to the lower gravity of space. It also discusses the role of the scientist in the space environment. It also discusses the potential uses of space development, particularly with the use of the space station.

Weber, Mary Ellen

2005-01-01

151

Computer/Information Science  

ERIC Educational Resources Information Center

Scholars representing the field of computer/information science were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might change our understanding. The scholars included Ken Birman, Jennifer Rexford, Tim Roughgarden, Margo Seltzer, Jim Spohrer, and…

Birman, Ken; Roughgarden, Tim; Seltzer, Margo; Spohrer, Jim; Stolterman, Erik; Kearsley, Greg; Koszalka, Tiffany; de Jong, Ton

2013-01-01

152

Planetary Science Space Physics  

E-print Network

. The mission was conceived to answer scientific questions about noctilucent clouds, including whether climate; our researchers define the technology required to collect data and answer scientific questions commitment to asking and answering the most exciting questions in planetary science, space physics, solar

Mojzsis, Stephen J.

153

Variability and Spectral Studies of Luminous Seyfert 1 Galaxy Fairall 9. Search for the Reflection Component is a Quasar: RXTE and ASCA Observation of a Nearby Radio-Quiet Quasar MR 2251-178  

NASA Technical Reports Server (NTRS)

Monitoring observations with interval of 3 days using RXTE (X Ray Timing Explorer) of the luminous Seyfert 1 galaxy Fairall 9 were performed for one year. The purpose of the observations were to study the variability of Fairall 9 and compare the results with those from the radio-loud object 3C 390.3. The data has been received and analysis is underway, using the new background model. An observation of the quasar MR 2251-178 was made in order to determine whether or not it has a reflection component. Older background models gave an unacceptable subtraction and analysis is underway using the new background model. The observation of NGC 6300 showed that the X-ray spectrum from this Seyfert 2 galaxy appears to be dominated by Compton reflection.

Leighly, Karen M.

1999-01-01

154

Electronic excitations in conducting polymers  

NASA Astrophysics Data System (ADS)

The subject of this dissertation is the excited electronic states of conducting polymers. With one exception, the experimental techniques used in this study are spectroscopies, in particular modulation spectroscopies. There are two major types of excited electronic states in conducting polymers: (1) excitons that have energies above the optical gap and (2) electronic excitations (here denoted 'excitations' as opposed to 'excitons') with energies below the optical gap. Excitations occur with a modulation of the bond length order; thus they are highly dependent on the topological structure of the polymer. In this study both excitons and excitations in conducting polymers with different topological structure are characterized, and their decay processes analyzed. The results are important for theoretical considerations, experimental work, and technological developments. This study provides evidence that the classical description of ?-conjugated polymers with a band model and neglecting electron-electron interactions must be reconsidered. Instead, a model that involves strong electron-electron interactions and takes into account the effects of disorder in real conducting polymers can describe the behavior of excitons and excitations (Chapter 5, Chapter 3). The results on exciton polarizability (Chapter 3) indicate that measurements of fast photocurrent must be explained in terms of exciton and excitation polarizability. This polarizability is highly dependent of the quality of the material (conjugation length distribution). A new experimental technique, electromodulated photoinduced absorption (EPA), is presented (Chapter 4) that allows the experimentalist to distinguish between photoinduced absorption signatures of different photoexcitations. The study (Chapter 5) on bisubstituted polyacetylenes shows how polymers must be engineered in order to achieve luminescence. The luminescence is not an effect of the topological structure of the material. It is an effect of the relative strength of electron-electron interactions that can be lowered with mechanical stress. This result is important for the development of light-emitting devices (LEDs) based on polymers. The work on the effect of electric fields on excitation and exciton kinetics in conducting polymers (Chapter 4) is also important for these kind of LEDs, since high electric fields in a conductive polymer film are necessary for their operation.

Liess, Martin Dieter

155

Excitation optimization for damage detection  

SciTech Connect

A technique is developed to answer the important question: 'Given limited system response measurements and ever-present physical limits on the level of excitation, what excitation should be provided to a system to make damage most detectable?' Specifically, a method is presented for optimizing excitations that maximize the sensitivity of output measurements to perturbations in damage-related parameters estimated with an extended Kalman filter. This optimization is carried out in a computationally efficient manner using adjoint-based optimization and causes the innovations term in the extended Kalman filter to be larger in the presence of estimation errors, which leads to a better estimate of the damage-related parameters in question. The technique is demonstrated numerically on a nonlinear 2 DOF system, where a significant improvement in the damage-related parameter estimation is observed.

Bement, Matthew T [Los Alamos National Laboratory; Bewley, Thomas R [UCSD

2009-01-01

156

Effects of dark atom excitations  

NASA Astrophysics Data System (ADS)

New stable quarks and charged leptons may exist and be hidden from detection, as they are bound by Coulomb interaction in neutral dark atoms of composite dark matter. This possibility leads to fundamentally new types of indirect effects related to the excitation of such dark atoms followed by their electromagnetic de-excitation. Stable -2 charged particles O--, bound to primordial helium in O-helium (OHe) atoms, represent the simplest model of dark atoms. Here we consider the structure of OHe atomic levels which is a necessary input for the indirect tests of such composite dark matter scenarios, and we give the spectrum of electromagnetic transitions from the levels excited in OHe collisions.

Cudell, Jean-Rene; Khlopov, Maxim Yu.; Wallemacq, Quentin

2014-11-01

157

The exciting thing about recombinant DNA, Victor McElhenySite: DNA Interactive (www.dnai.org)  

NSDL National Science Digital Library

` Victor McElheny DNAi Location:Manipulation>Revolution>players>The controversy A new world of exploration Former science journalist Victor McElheny muses on the excitement that surrounded the new genetic technology.

2008-03-26

158

Waveguide-excited fluorescence microarray  

NASA Astrophysics Data System (ADS)

Signal-to-noise ratio is a crucial issue in microarray fluorescence read-out. Several strategies are proposed for its improvement. First, light collection in conventional microarrays scanners is quite limited. It was recently shown that almost full collection can be achieved in an integrated lens-free biosensor, with labelled species hybridizing practically on the surface of a sensitive silicon detector [L. Martinelli et al. Appl. Phys. Lett. 91, 083901 (2007)]. However, even with such an improvement, the ultimate goal of real-time measurements during hybridization is challenging: the detector is dazzled by the large fluorescence of labelled species in the solution. In the present paper we show that this unwanted signal can effectively be reduced if the excitation light is confined in a waveguide. Moreover, the concentration of excitation light in a waveguide results in a huge signal gain. In our experiment we realized a structure consisting of a high index sol-gel waveguide deposited on a low-index substrate. The fluorescent molecules deposited on the surface of the waveguide were excited by the evanescent part of a wave travelling in the guide. The comparison with free-space excitation schemes confirms a huge gain (by several orders of magnitude) in favour of waveguide-based excitation. An optical guide deposited onto an integrated biosensor thus combines both advantages of ideal light collection and enhanced surface localized excitation without compromising the imaging properties. Modelling predicts a negligible penalty from spatial cross-talk in practical applications. We believe that such a system would bring microarrays to hitherto unattained sensitivities.

Sagarzazu, Gabriel; Bedu, Mélanie; Martinelli, Lucio; Ha, Khoi-Nguyen; Pelletier, Nicolas; Safarov, Viatcheslav I.; Weisbuch, Claude; Gacoin, Thierry; Benisty, Henri

2008-04-01

159

SCIENCE CHINA Technological Sciences  

E-print Network

SCIENCE CHINA Technological Sciences © Science China Press and Springer-Verlag Berlin Heidelberg and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China; 2 Institute of Theoretical Physics, Lanzhou University, Lanzhou 730000, China; 3 School of Material Science and Engineering, Georgia Institute

Wang, Zhong L.

160

SCIENCE CHINA Earth Sciences  

E-print Network

SCIENCE CHINA Earth Sciences © Science China Press and Springer-Verlag Berlin Heidelberg 2010 earth-010-0056-5 Growth characteristics and response to climate change of Larix Miller tree-ring in China SUN Yu1,4 , WANG Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; 2 Institute

Zhang, Qi-Bin

161

NRC Earth Science Decadal Survey-Mission Concept Earth Sciences from the Astronomer's Perspective, a Deep  

E-print Network

NRC Earth Science Decadal Survey-Mission Concept Earth Sciences from the Astronomer's Perspective Irina Melnikova #12;1 Earth Sciences from the Astronomer's Perspective 1.0 Mission Concept and Purpose Earth observations from satellites located in deep space offer the exciting opportunity to look

Christian, Eric

162

Cardiac excitation–contraction coupling  

Microsoft Academic Search

Of the ions involved in the intricate workings of the heart, calcium is considered perhaps the most important. It is crucial to the very process that enables the chambers of the heart to contract and relax, a process called excitation–contraction coupling. It is important to understand in quantitative detail exactly how calcium is moved around the various organelles of the

Donald M. Bers

2002-01-01

163

Perceptual Load Alters Visual Excitability  

ERIC Educational Resources Information Center

Increasing perceptual load reduces the processing of visual stimuli outside the focus of attention, but the mechanism underlying these effects remains unclear. Here we tested an account attributing the effects of perceptual load to modulations of visual cortex excitability. In contrast to stimulus competition accounts, which propose that load…

Carmel, David; Thorne, Jeremy D.; Rees, Geraint; Lavie, Nilli

2011-01-01

164

Science in motion  

SciTech Connect

With the help of grants from the National Science Foundation, the Howard Hughes Medical Institute and other sponsors, we have instituted a program that provides total support for the high school science teacher. Using specially designed vans, certified science teachers deliver modern scientific instrumentation to schools and support the teacher in introducing the students to the use of this equipment. Summer programs and science fairs are available where teachers have the opportunity to use the equipment and develop experiments for their classrooms. The activities of this program offer students and faculty the opportunity to demonstrate the attainment of national standards. This program has been featured on ABC news as a successful program in exciting students about science using a hands-on approach.

Anderson, M.; Howe, D.; Mitchell, D. [Juniata College, Huntingdon, PA (United States)

1994-12-31

165

Computer Science Teachers Association  

NSDL National Science Digital Library

The Computers Science Teachers Association (CSTA) is a professional organization that helps teachers in the field learn about professional development opportunities, along with offering them the opportunity to network. This section of then CSTA's website provides access to over a dozen helpful resources, including an instructional video and a college selection website. First-time visitors should check out the Quizzes with a Theme. Here they will find a set of computer science themed quizzes developed by Professor Bruce Maxwell of Colby College. Also, the CS Unplugged Videos area is quite a bit of fun. The videos here include a one-hour computer science show in which students encounter many concepts from computer science, along with short clips of activities that can be used in the classroom. Additionally, the site includes a selection of computer games designed for young women and a link to resources promoting excitement about computer science from Carnegie Mellon University.

166

Response of an unbalanced rotating machine to a stationary normal random excitation  

E-print Network

RESPONSE OF AN UNBALANCED ROTATING MACHINE TO A STATIONARY NORMAL RANDOM EXCITATION A Thesis by LOLA BOYCE Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER... OF SCIENCE August 1975 Major Subject: Mechanical Engineering RESPONSE OF AN UNBALANCED ROTATING MACHINE TO A STATIONARY NORMAL RANDOM EXCITATION A Thesis by LOLA BOYCE Approved as to style and content by: C a ma Committee Head o e artment Membe...

Boyce, Lola

2012-06-07

167

The excited state geometry associated with the 2900A absorption spectrum of sulfur dioxide  

E-print Network

O THE EXCITED STATE GEOMETRY ASSOCIATED WITH THE 2900A ABSORPTION SPECTRUM OF SULFUR DIOXIDE A Thesis By DAVID ROBERT SMITH& JR. Submitted to the Graduate School of the Agricultural and Mechanical College of Texas in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE August, 1962 Major Subject: Physics THE EXCITED STATE GEOMETRY ASSOCIATED WITH THE 2900A ABSORPTION SPECTRUM OF SULFUR DIOXIDE A Thesis By DAVID ROBERT SMITH, JR. Approved as to style and content by...

Smith, David Robert, Jr

1962-01-01

168

Excited states of porphyrin macrocycles.  

PubMed

S1 --> S(n) spectra of porphyrin, diprotonated porphyrin, and tetraoxaporphyrin dication have been measured in the energy range 2-3 eV above S1 at room temperature in solution by means of transient absorption spectroscopy exciting with femtosecond pulses. Highly excited pi pi* states not active in the conventional S0 --> S(n) spectrum have been observed. The experimental data are discussed on the basis of the time dependent density functional theory taking advantage of large scale calculations of configuration interaction between singly excited configurations (DF/SCI). The DF/SCI calculation on porphyrin has allowed to assign g states active in the S1 --> S(n) spectrum. Applying the same calculation method to tetraoxaporphyrin dication the S0 --> S(n) spectrum is reproduced relatively to the Q and B (Soret) bands as well as to the weaker E(u) bands at higher energy. According to our calculation the S1 --> S(n) transient spectrum is related to states of g symmetry mainly arising from excitations between doubly degenerate pi and pi* orbitals such as 2e(g) --> 4e(g). In the case of diprotonated porphyrin it is shown that the complex of the macrocycle with two trifluoroacetate anions plays a significant role for absorption. Charge transfer excitations from the anions to the macrocycle contribute to absorption above the Soret band, justifying the intensity enhancement of the S0 --> S(n) spectrum with respect to the other two macrocyclic systems. PMID:18855369

Moroni, Laura; Gellini, Cristina; Salvi, Pier Remigio; Marcelli, Agnese; Foggi, Paolo

2008-11-01

169

Goddard's Astrophysics Science Division Annual Report 2011  

NASA Technical Reports Server (NTRS)

The Astrophysics Science Division(ASD) at Goddard Space Flight Center(GSFC)is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum from gamma rays to radiowavelengths as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, space-based interferometry, high contract imaging techniques to serch for exoplanets, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. The overriding goals of ASD are to carry out cutting-edge scientific research, and provide Project Scientist support for spaceflight missions, implement the goals of the NASA Strategic Plan, serve and suppport the astronomical community, and enable future missions by conceiving new conepts and inventing new technologies.

Centrella, Joan; Reddy, Francis; Tyler, Pat

2012-01-01

170

The Astrophysics Science Division Annual Report 2009  

NASA Technical Reports Server (NTRS)

The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum - from gamma rays to radio wavelengths - as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions - WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, space-based interferometry, high contrast imaging techniques to search for exoplanets, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. The overriding goals of ASD are to carry out cutting-edge scientific research, provide Project Scientist support for spaceflight missions, implement the goals of the NASA Strategic Plan, serve and support the astronomical community, and enable future missions by conceiving new concepts and inventing new technologies.

Oegerle, William (Editor); Reddy, Francis (Editor); Tyler, Pat (Editor)

2010-01-01

171

Science and Science Fiction  

NSDL National Science Digital Library

This creative activity weaves science fiction and language arts skills into the science classroom, which can expand and enrich the science content and abstract concepts found in science textbooks.Well-written literature can be used to open new ways of learning and understanding while developing critical thinking skills for students of all abilities.

David Oravetz

2005-03-01

172

Autoresonant excitation of dark solitons.  

PubMed

Continuouslyphase-locked (autoresonant) dark solitons of the defocusing nonlinear Schrodinger equation are excited and controlled by driving the system by a slowly chirped wavelike perturbation. The theory of these excitations is developed using Whitham's averaged variational principle and compared with numerical simulations. The problem of the threshold for transition to autoresonance in the driven system is studied in detail, focusing on the regime when the weakly nonlinear frequency shift in the problem differs from the typical quadratic dependence on the wave amplitude. The numerical simulations in this regime show a deviation of the autoresonance threshold on the driving amplitude from the usual 3/4 power dependence on the driving frequency chirp rate. The theory of this effect is suggested. PMID:25679688

Borich, M A; Shagalov, A G; Friedland, L

2015-01-01

173

Dipole excitations in 96Ru  

NASA Astrophysics Data System (ADS)

Candidates for the two-phonon quadrupole-octupole 1- state and the two-phonon mixed-symmetry 1+ms state have been identified in the N=52 isotope 96Ru using the nuclear resonance fluorescence technique at the bremsstrahlung facility of the Stuttgart Dynamitron accelerator. Detailed information on energies, spins, branching ratios, and transition strengths of four new dipole excitations in 96Ru have been obtained. The observed dipole excitations are nearly at the same energies as in 94Mo, and the transition probabilities are comparable to those for the decay of the (2+1?3-1)1- and the (2+1?2+ms)1+ms states in 94Mo.

Linnemann, A.; Fransen, C.; Gorska, M.; Jolie, J.; Kneissl, U.; Knoch, P.; Mücher, D.; Pitz, H. H.; Scheck, M.; Scholl, C.; Brentano, P. Von

2005-12-01

174

Spatiotemporal control of nanooptical excitations  

PubMed Central

The most general investigation and exploitation of light-induced processes require simultaneous control over spatial and temporal properties of the electromagnetic field on a femtosecond time and nanometer length scale. Based on the combination of polarization pulse shaping and time-resolved two-photon photoemission electron microscopy, we demonstrate such control over nanoscale spatial and ultrafast temporal degrees of freedom of an electromagnetic excitation in the vicinity of a nanostructure. The time-resolved cross-correlation measurement of the local photoemission yield reveals the switching of the nanolocalized optical near-field distribution with a lateral resolution well below the diffraction limit and a temporal resolution on the femtosecond time scale. In addition, successful adaptive spatiotemporal control demonstrates the flexibility of the method. This flexible simultaneous control of temporal and spatial properties of nanophotonic excitations opens new possibilities to tailor and optimize the light–matter interaction in spectroscopic methods as well as in nanophotonic applications. PMID:20212153

Aeschlimann, Martin; Bauer, Michael; Bayer, Daniela; Brixner, Tobias; Cunovic, Stefan; Dimler, Frank; Fischer, Alexander; Pfeiffer, Walter; Rohmer, Martin; Schneider, Christian; Steeb, Felix; Strüber, Christian; Voronine, Dmitri V.

2010-01-01

175

Multiphoton-Excited Serotonin Photochemistry  

PubMed Central

We report photochemical and photophysical studies of a multiphoton-excited reaction of serotonin that previously has been shown to generate a photoproduct capable of emitting broadly in the visible spectral region. The current studies demonstrate that absorption of near-infrared light by an intermediate state prepared via three-photon absorption enhances the photoproduct formation yield, with the largest action cross sections (?10?19 cm2) observed at the short-wavelength limit of the titanium:sapphire excitation source. The intermediate state is shown to persist for at least tens of nanoseconds and likely to be different from a previously reported oxygen-sensitive intermediate. In addition, the two-photon fluorescence action spectrum for the fluorescent photoproduct was determined and found to have a maximum at ?780 nm (3.2 eV). A general mechanism for this photochemical process is proposed. PMID:15111435

Gostkowski, Michael L.; Allen, Richard; Plenert, Matthew L.; Okerberg, Eric; Gordon, Mary Jane; Shear, Jason B.

2004-01-01

176

Receiver-exciter controller design  

NASA Astrophysics Data System (ADS)

A description of the general design of both the block 3 and block 4 receiver-exciter controllers for the Deep Space Network (DSN) Mark IV-A System is presented along with the design approach. The controllers are designed to enable the receiver-exciter subsystem (RCV) to be configured, calibrated, initialized and operated from a central location via high level instructions. The RECs are designed to be operated under the control of the DMC subsystem. The instructions are in the form of standard subsystem blocks (SSBs) received via the local area network (LAN). The centralized control provided by RECs and other DSCC controllers in Mark IV-A is intended to reduce DSN operations costs from the Mark III era.

Jansma, P. A.

1982-06-01

177

Receiver-exciter controller design  

NASA Technical Reports Server (NTRS)

A description of the general design of both the block 3 and block 4 receiver-exciter controllers for the Deep Space Network (DSN) Mark IV-A System is presented along with the design approach. The controllers are designed to enable the receiver-exciter subsystem (RCV) to be configured, calibrated, initialized and operated from a central location via high level instructions. The RECs are designed to be operated under the control of the DMC subsystem. The instructions are in the form of standard subsystem blocks (SSBs) received via the local area network (LAN). The centralized control provided by RECs and other DSCC controllers in Mark IV-A is intended to reduce DSN operations costs from the Mark III era.

Jansma, P. A.

1982-01-01

178

Singleparticle excitations in 89Y  

Microsoft Academic Search

Inelastic-electron-scattering cross sections have been measured for the first three excitations in 89Y at forward angles for momentum transfers of 1.25

J. E. Wise; F. W. Hersman; J. H. Heisenberg; T. E. Milliman; J. P. Connelly; J. R. Calarco; C. N. Papanicolas

1990-01-01

179

Wedding ring shaped excitation coil  

DOEpatents

A high frequency inductively coupled electrodeless lamp includes an excitation coil with an effective electrical length which is less than one half wavelength of a driving frequency applied thereto, preferably much less. The driving frequency may be greater than 100 MHz and is preferably as high as 915 MHz. Preferably, the excitation coil is configured as a non-helical, semi-cylindrical conductive surface having less than one turn, in the general shape of a wedding ring. At high frequencies, the current in the coil forms two loops which are spaced apart and parallel to each other. Configured appropriately, the coil approximates a Helmholtz configuration. The lamp preferably utilizes an bulb encased in a reflective ceramic cup with a pre-formed aperture defined therethrough. The ceramic cup may include structural features to aid in alignment and/or a flanged face to aid in thermal management. The lamp head is preferably an integrated lamp head comprising a metal matrix composite surrounding an insulating ceramic with the excitation integrally formed on the ceramic. A novel solid-state oscillator preferably provides RF power to the lamp. The oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency.

MacLennan, Donald A. (Gaithersburg, MD); Tsai, Peter (Olney, MD)

2001-01-01

180

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2014 CFR

...In particular, no static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type exciter that has the capability of voltage build-up after two months of no operation....

2014-10-01

181

Search for excited neutrinos in Z decay  

Microsoft Academic Search

Excited neutrinos decaying into a neutrino and a photon are searched for in the ALEPH detector at LEP. No evidence is found for Z decay into v¯v* or v¯*v* final states. Upper limits are derived on excited neutrino couplings up to excited neutrino masses close to the Z mass. Lower limits on the v* mass, independent of the v* decay

D. Decamp; B. Deschizeaux; C. Goy; J.-P. Lees; M.-N. Minard; R. Alemany; J. M. Crespo; M C Delfino; E. Fernandez; V. Gaitan; Ll. Garrido; P. Mato; R. Miguel; Ll. M. Mir; S. Orteu; A. Pacheco; J. A. Perlas; E. Tubau; M. G. Catanesi; D. Creanza; M. de Palma; A. Farilla; G. Iaselli; G. Maggi; M. Maggi; S. Natali; S. Nuzzo; M. Quattromini; A. Ranieri; G. Raso; F Ruggieri; G. Selvaggi; L. Silvestris; P. Tempesta; G. Zito; Y. S. Gao; H. Hu; D. Huang; S. Jin; J. Lin; T. Ruan; T. Wang; W. Wu; Y. Xie; D. Xu; R. Xu; J. Zhang; W. Zhao; W. B. Atwood; F. Bird; E. Blucher; G. Bonvicini; F. Bossi; J. Bourotte; D. Brown; T. H. Burnett; H. Drevermann; Friedrich Dydak; R. W. Forty; C. Grab; R. Hagelberg; S. Haywood; B. Jost; M. Kasemann; G. Kellner; J. Knobloch; A. Lacourt; I. Lehraus; T. Lohse; A. Marchioro; M. Martinez; S. Menary; A. Minten; A. Miotto; J. Nash; P. Palazzi; F. Ranjard; G. Redlinger; A. Roth; J. Rothberg; H. Rotscheidt; W. von Rüden; R. St. Denis; D. Schlatter; M. Takashima; M. Talby; H. Taureg; W. Tejessy; H. Wachsmuth; S. Wasserbaech; S. Wheeler; W. Wiedenmann; W. Witzeling; J. Wotschack; Z. Ajaltouni; M. Bardadin-Otwinowska; A. Falvard; R. El Fellous; P. Gay; P. Henrard; J. Jousset; B. Michel; J.-C. Montret; D. Pallin; P. Perret; J. Proriol; F. Prulhière; J. D. Hansen; J. R. Hansen; P. H. Hansen; R. Møllerud; B. S. Nilsson; G. Petersen; I. Efthymiopoulos; E. Simopoulou; A. Vayaki; J. Badier; A. Blondel; G. Bonneaud; F. Braems; J. C. Brient; G. Fouque; A. Gamess; R. Guirlet; A. Rosowsky; A. Rougé; M. Rumpf; R. Tanaka; H. Videau; I. Videau; D. J. Candlin; G. Parrini; M. Corden; C. Georgiopoulos; M. Ikeda; J. Lannutti; D. Levinthal; M. Mermikides; L. Sawyer; G. Stimpfl; A. Antonelli; R. Baldini; G. Bencivenni; G. Bologna; P. Campana; G. Capon; V. Chiarella; B. D'Ettorre-Piazzoli; G. Felici; P. Laurelli; G. Mannocchi; F. Massimo-Brancacci; F. Murtas; G. P. Murtas; G. Nicoletti; M. Pepe-Altarelli; P. Picchi; P. Zografou; B. Altoon; O. Boyle; A. W. Halley; I. Ten Have; J. L. Hearns; J. G. Lynch; W. T. Morton; C. Raine; J. M. Scarr; K. Smith; A. S. Thompson; B. Brandl; O. Braun; R. Geiges; C. Geweniger; P. Hanke; V. Hepp; E. E. Kluge; Y. Maumary; A. Putzer; B. Rensch; A. Stahl; K. Tittel; M. Wunsch; A. T. Belk; R. Beuselinck; D. M. Binnie; W. Cameron; M. Cattaneo; P. J. Dornan; S. Dugeay; A. M. Greene; J. F. Hassard; S. J. Patton; J. K. Sedgbeer; G. Taylor; I. R. Tomalin; A. G. Wright; P. Girtler; D. Kuhn; G. Rudolph; C. K. Bowdery; T. J. Brodbeck; A. J. Finch; F. Foster; G. Hughes; N. R. Keemer; M. Nuttall; B. S. Rowlingson; T. Sloan; S. W. Snow; T. Barczewski; L. A. T. Bauerdick; K. Kleinknecht; B. Renk; S. Roehn; H.-G. Sander; M. Schmelling; F. Steeg; J.-P. Albanese; J.-J. Aubert; C. Benchouk; V. Bernard; A. Bonissent; D. Courvoisier; F. Etienne; S. Papalexiou; P. Payre; B. Pietrzyk; Z. Qian; W. Blum; P. Cattaneo; G. Cowan; B. Dehning; H. Dietl; M. Fernandez-Bosman; A. Jahn; E. Lange; G. Lütjens; G. Lutz; W. Männer; H.-G. Moser; Y. Pan; R. Richter; A. S. Schwarz; R. Settles; U. Stiegler; U. Stierlin; J. Thomas; V. Bertin; G. de Bouard; J. Boucrot; O. Callot; X. Chen; A. Cordier; M. Davier; G. Ganis; J.-F. Grivaz; Ph. Heusse; P. Janot; V. Journé; D. W. Kim; J. Lefrançois; A.-M. Lutz; J.-J. Veillet; Z. Zhang; F. Zomer; S. R. Amendolia; G. Bagliesi; G. Batignani; L. Bosisio; U. Bottigli; C. Bradaschia; M. A. Ciocci; I. Ferrante; F. Fidecaro; L. Foà; E. Focardi; F. Forti; A. Giassi; M. A. Giorgi; F. Ligabue; A. Lusiani; E. B. Mannelli; P. S. Marrocchesi; A. Messineo; F. Palla; G. Sanguinetti; J. Steinberger; R. Tenchini; G Triggiani; J. M. Carter; M. G. Green; P. V. March; T. Medcalf; M. R. Saich; J. A. Strong; R. M. Thomas; T. Wildish; D. R. Botterill; R. W. Clifft; T. R. Edgecock; M. Edwards; S. M. Fisher; J. Harvey; T. J. Jones; P. R. Norton; D. P. Salmon; J. C. Thompson; B. Bloch-Devaux; P. Colas; C. Klopfenstein; E. Lançon; E. Locci; S. Loucatos; L. Mirabito; E. Monnier; P. Perez; F. Perrier; J. Rander; J.-F. Renardy; A. Roussarie; J.-P. Schuller; J. G. Ashman; C. N. Booth; F. Combley; M. Dinsdale; J. Martin; D. Parker; L. F. Thompson; S. Brandt; H. Burkhardt; C. Grupen; H. Meinhard; E. Neugebauer; U. Schäfer; H. Seywerd; G. Apollinari; G. Giannini; B. Gobbo; F. Liello; E. Milotti; L. Rolandi; L. Bellantoni; J. F. Boudreau; D. Cinabro; J. S. Conway; D. F. Cowen; A. J. Deweerd; Z. Feng; D. P. S. Ferguson; J. L. Harton; J. Hilgart; J. E. Jacobsen; R. C. Jared; R. P. Johnson; B. W. Leclaire; T. Parker; J. R. Pater; Y. Saadi; V. Sharma; J. A. Wear; F. V. Weber; Sau Lan Wu; G. Zobernig

1990-01-01

182

Peculiarities of collisional excitation transfer with excited screened energy levels of atoms  

SciTech Connect

We report an experimental discovery of deviations from the known regularities in collisional excitation transfer processes for metal atoms. The collisional excitation transfer with excited screened energy levels of thulium and dysprosium atoms is studied. The selecting role of the screening 6s shell in collisional excitation transfer is shown.

Gerasimov, V. A. [Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation); Gerasimov, V. V. [Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation); Department of Physics, Tomsk State University, Tomsk, 634050 (Russian Federation); Pavlinskiy, A. V. [Institute of High Current Electronics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation)

2007-09-15

183

Inwardly rotating spirals in nonuniform excitable media.  

PubMed

Inwardly rotating spirals (IRSs) have attracted great attention since their observation in an oscillatory reaction-diffusion system. However, IRSs have not yet been reported in planar excitable media. In the present work we investigate rotating waves in a nonuniform excitable medium, consisting of an inner disk part surrounded by an outer ring part with different excitabilities, by numerical simulations of a simple FitzHugh-Nagumo model. Depending on the excitability of the medium as well as the inhomogeneity, we find the occurrence of IRSs, of which the excitation propagates inwardly to the geometrical spiral tip. PMID:22400649

Gao, Xiang; Feng, Xia; Cai, Mei-chun; Li, Bing-wei; Ying, He-ping; Zhang, Hong

2012-01-01

184

Laptops--An Exciting Addition to the Social Science Classroom.  

ERIC Educational Resources Information Center

Describes ways laptop computers are used in two high school Advanced Placement History classes. Discusses notetaking on laptops, small group assignments via modem, cooperative-learning groups, and laptops as a research tool. (SR)

Riegler, Edward R.

1992-01-01

185

SCIENCE CAREERS AT EPA: AN EXCITING OPPORTUNITY TO SERVE  

EPA Science Inventory

The Environmental Protection Agency has 30 years of history protecting the environment and human health. The scientists at EPA have different backgrounds and experiences that contribute to the creativity of research and development of risk assessment techniques. An overview o...

186

Partnership in Science Education  

NSDL National Science Digital Library

This is an outline for an exchange of scientific and cultural information between high schools in different regions of the world. This activity outlines a recent exchange between a high school in New Hampshire and a high school in Guam. Scientific Exchange included: Acid Rain, Air Quality, Photo Essays of the Regions, Plant and Animal Comparisons, and Earth Science Studies. The Exchange proved to be an exciting collaboration for both schools.

BEGIN:VCARD VERSION:2.1 FN:Stephen Bartsch N:Bartsch;Stephen ORG:Conval High School REV:2005-04-12 END:VCARD

1995-06-30

187

Science Sampler: Mapping variables  

NSDL National Science Digital Library

One of the biggest obstacles students encounter during the inquiry process is conducting valid investigations. Many students get caught up in the questions they have, the variety of materials they have access to, and the excitement of "doing" science. One way to help students organize their thoughts when designing inquiry investigations is to have them map out their thoughts and identify all of the variables in the investigations.

Marsha Bednarski

2006-10-01

188

Turbulent swirling jets with excitation  

NASA Technical Reports Server (NTRS)

An existing cold-jet facility at NASA Lewis Research Center was modified to produce swirling flows with controllable initial tangential velocity distribution. Two extreme swirl profiles, i.e., one with solid-body rotation and the other predominated by a free-vortex distribution, were produced at identical swirl number of 0.48. Mean centerline velocity decay characteristics of the solid-body rotation jet flow exhibited classical decay features of a swirling jet with S - 0.48 reported in the literature. However, the predominantly free-vortex distribution case was on the verge of vortex breakdown, a phenomenon associated with the rotating flows of significantly higher swirl numbers, i.e., S sub crit greater than or equal to 0.06. This remarkable result leads to the conclusion that the integrated swirl effect, reflected in the swirl number, is inadequate in describing the mean swirling jet behavior in the near field. The relative size (i.e., diameter) of the vortex core emerging from the nozzle and the corresponding tangential velocity distribution are also controlling factors. Excitability of swirling jets is also investigated by exciting a flow with a swirl number of 0.35 by plane acoustic waves at a constant sound pressure level and at various frequencies. It is observed that the cold swirling jet is excitable by plane waves, and that the instability waves grow about 50 percent less in peak r.m.s. amplitude and saturate further upstream compared to corresponding waves in a jet without swirl having the same axial mass flux. The preferred Strouhal number based on the mass-averaged axial velocity and nozzle exit diameter for both swirling and nonswirling flows is 0.4.

Taghavi, Rahmat; Farokhi, Saeed

1988-01-01

189

Electron beam excitation of surface plasmon polaritons.  

PubMed

In this paper, the excitations of surface plasmon polaritons (SPPs) by both perpendicular and parallel electron beam are investigated. The results of analytical theory and numerical calculation show that the mechanisms of these two excitations are essentially different, and the behavior and properties of SPPs in metal structures strongly depend on the methods of excitation. For the perpendicular excitation, SPPs contain plenty of frequency components, propagate with attenuation and are always accompanied with the transition radiation. Whereas for parallel excitation, SPPs waves are coherent, tunable, propagating without attenuation and the transition radiation does not occur. We also show that there are two modes for the parallel excited SPPs on the metal films and they all can be excited efficiently by the parallel moving electron beam. And the operating frequency of SPPs can be tuned in a large frequency range by adjusting the beam energy. PMID:25321010

Gong, Sen; Hu, Min; Zhong, Renbin; Chen, Xiaoxing; Zhang, Ping; Zhao, Tao; Liu, Shenggang

2014-08-11

190

Collective excitations in the continuum  

SciTech Connect

Pairing (particle-particle) giant resonances are analyzed within a shell-model formalism in the complex energy plane with the aim of understanding why they have not been observed so far. A comparison is made with the equivalent particle-hole mode by applying the formalism to the analysis of the well-understood particle-hole giant resonance. It is found that because of the proper treatment of the continuum intrinsic to the formalism, giant pairing resonances lie much higher than previously predicted and that some of them may be too wide to be observed, whereas others are meaningful excitations. For these, new experimental searches are proposed.

Dussel, G. G. [Departamento de Fisica, FCEyN-UBA, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Betan, R. Id [Departamento de Quimica y Fisica, FCEIA (UNR)-Instituto de Fisica Rosario, IFIR (CONICET), 2000 Rosario (Argentina); Liotta, R. J. [KTH, Alba Nova University Center, S-10691 Stockholm (Sweden); Vertse, T. [Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen (Hungary); Faculty of Informatics, University of Debrecen, H-4010 Debrecen (Hungary)

2009-12-15

191

High Frequency Chandler Wobble Excitation  

NASA Astrophysics Data System (ADS)

Variations of Earth rotation on sub-daily to secular timescales are caused by mass redistributions in the Earth system as a consequence of geophysical processes and gravitational influences. Forced oscillations of polar motion are superposed by free oscillations of the Earth, i.e. the Chandler wobble and the free core nutation. In order to study the interactions between externally induced polar motion and the Earth's free oscillations, a non-linear gyroscopic model has been developed. In most of the former investigations on polar motion, the Chandler wobble is introduced as a damped oscillation with predetermined frequency and amplitude. However, as the effect of rotational deformation is a backcoupling mechanism of polar motion on the Earth's rotational dynamics, both period and amplitude of the Chandler wobble are time-dependent when regarding additional excitations from, e.g., atmospheric or oceanic mass redistributions. The gyroscopic model is free of any explicit information concerning amplitude, phase, and period of free oscillations. The characteristics of the Earth's free oscillation is reproduced by the model from rheological and geometrical parameters and rotational deformation is taken into account. This enables to study the time variable Chandler oscillation when the gyro is forced with atmospheric and oceanic angular momentum from the global atmospheric ECHAM3-T21 general circulation model together with the ocean model for circulation and tides OMCT driven by ECHAM including surface pressure. Besides, mass redistributions in the Earth's body due to gravitational and loading deformations are regarded and external torques exerted by Moon and Sun are considered. The numerical results of the gyro are significantly related with the geodetically observed time series of polar motion published by the IERS. It is shown that the consistent excitation is capable to counteract the damping and thus to maintain the Chandler amplitude. Spectral analyses of the ECHAM and OMCT forcing fields give no hint for increased excitation power in the Chandler band. Thus it is assumed, that continuous high frequency excitation due to stochastic weather phenomena is responsible for the perpetuation of the Chandler wobble.

Seitz, F.; Stuck, J.; Thomas, M.

2003-04-01

192

Sloshing motions in excited tanks  

NASA Astrophysics Data System (ADS)

A fully non-linear finite difference model has been developed based on inviscid flow equations. Numerical experiments of sloshing wave motion are undertaken in a 2-D tank which is moved both horizontally and vertically. Results of liquid sloshing induced by harmonic base excitations are presented for small to steep non-breaking waves. The simulations are limited to a single water depth above the critical depth corresponding to a tank aspect ratio of hs/ b=0.5. The numerical model is valid for any water depth except for small depth when viscous effects would become important. Solutions are limited to steep non-overturning waves. Good agreement for small horizontal forcing amplitude is achieved between the numerical model and second order small perturbation theory. For large horizontal forcing, non-linear effects are captured by the third-order single modal solution and the fully non-linear numerical model. The agreement is in general good, both amplitude and phase. As expected, the third-order compared to the second-order solution is more accurate. This is especially true for resonance, high forcing frequency and mode interaction cases. However, it was found that multimodal approximate forms should be used for the cases in which detuning effects occur due to mode interaction. We present some test cases where detuning effects are evident both for single dominant modes and mode interaction cases. Furthermore, for very steep waves, just before the waves overturn, and for large forcing frequency, a discrepancy in amplitude and phase occurs between the approximate forms and the numerical model. The effects of the simultaneous vertical and horizontal excitations in comparison with the pure horizontal motion and pure vertical motion is examined. It is shown that vertical excitation causes the instability associated with parametric resonance of the combined motion for a certain set of frequencies and amplitudes of the vertical motion while the horizontal motion is related to classical resonance. It is also found that, in addition to the resonant frequency of the pure horizontal excitation, an infinite number of additional resonance frequencies exist due to the combined motion of the tank. The dependence of the non-linear behaviour of the solution on the wave steepness is discussed. It is found that for the present problem, non-linear effects become important when the steepness reaches about 0.1, in agreement with the physical experiments of Abramson [Rep. SP 106, NASA, 1966].

Frandsen, Jannette B.

2004-05-01

193

Physical Science Earth Science  

E-print Network

Navigation Front Page Physical Science Earth Science Biology Medicine Neuroscience Culture Applied removes the template and converts the resulting copper oxide structures to pure metal, retaining Medicine Neurosciences Culture Search Featured Articles More Open Collaboration for Drug Design Camphor

Bennett, Gisele

194

Science in Science Fiction.  

ERIC Educational Resources Information Center

Offers some suggestions as to how science fiction, especially television science fiction programs such as "Star Trek" and "Star Wars", can be drawn into physics lessons to illuminate some interesting issues. (Author/KHR)

Allday, Jonathan

2003-01-01

195

Entropy Driven Atomic Motion in Laser-Excited Bismuth  

SciTech Connect

We introduce a thermodynamical model based on the two-temperature approach in order to fully understand the dynamics of the coherent A{sub 1g} phonon in laser-excited bismuth. Using this model, we simulate the time evolution of (111) Bragg peak intensities measured by Fritz et al.[Science 315, 633 (2007)] in femtosecond x-ray diffraction experiments performed on a bismuth film for different laser fluences. The agreement between theoretical and experimental results is striking not only because we use fluences very close to the experimental ones but also because most of the model parameters are obtained from ab initio calculations performed for different electron temperatures.

Giret, Y.; Gelle, A.; Arnaud, B. [Institut de Physique de Rennes (IPR), UMR UR1-CNRS 6251, Campus de Beaulieu-Bat 11 A, 35042 Rennes Cedex, France, EU (France)

2011-04-15

196

Science Camp: Just for the Girls  

ERIC Educational Resources Information Center

Research shows that girls tend to lose interest in science and math as they move through the education pipeline--a retreat that often begins during middle school. Summer science camps can be part of reversing that trend, some say. Academic camps are on the rise across the country, including ones to get adolescent girls excited about the…

Cavanagh, Sean

2007-01-01

197

SCIENCE CHINA Technological Sciences  

E-print Network

SCIENCE CHINA Technological Sciences © Science China Press and Springer-Verlag Berlin Heidelberg. Density-functional-theory formulation of classical and quantum Hooke's law. Sci China Tech Sci, 2014, 57- sider an equilibrium lattice without strain (=0), but elec- #12;Hu H, et al. Sci China Tech Sci April

Simons, Jack

198

SCIENCE CHINA Life Sciences  

E-print Network

SCIENCE CHINA Life Sciences © The Author(s) 2011. This article is published with open access for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001, China; 2 School of Chemistry and Environmental Engineering, Harbin University of Science and Technology, Harbin 150040, China

Zheng, Yufeng

199

SCIENCE CHINA Life Sciences  

E-print Network

SCIENCE CHINA Life Sciences © Science China Press and Springer-Verlag Berlin Heidelberg 2010 life. The olfactory circuit of the fruit fly Drosophila melanogaster. Sci China Life Sci, 2010, 53: 472­484, doi: 10 similarity with the #12;Liang Liang, et al. Sci China Life Sci April (2010) Vol.53 No.4 473 Figure 1 Scheme

Luo, Liqun

200

SCIENCE CHINA Information Sciences  

E-print Network

. REVIEW . SCIENCE CHINA Information Sciences August 2011 Vol. 54 No. 8: 1547­1561 doi: 10.1007/s11432-011-4306-8 c Science China Press and Springer-Verlag Berlin Heidelberg 2011 info.scichina.com wwwSchool of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China; 2State

Xia, Xiang-Gen

201

Coulomb excitation of 73Ga  

E-print Network

The B(E2; Ii -> If) values for transitions in 71Ga and 73Ga were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of 71,73Ga at the REX-ISOLDE on-line isotope mass separator facility. The emitted gamma rays were detected by the MINIBALL-detector array and B(E2; Ii->If) values were obtained from the yields normalized to the known strength of the 2+ -> 0+ transition in the 120Sn target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity towards lower excitation energy when adding neutrons beyond N = 40. This supports conclusions from previous studies of the gallium isotopes which indicated a structural change in this isotopical chain between N = 40 and N = 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2- spin and parity for the ground state, the extracted results revealed evidence for a 1/2-; 3/2- doublet near the ground state in 73 31Ga42 differing by at most 0.8 keV in energy.

J. Diriken; I. Stefanescu; D. Balabanski; N. Blasi; A. Blazhev; N. Bree; J. Cederkäll; T. E. Cocolios; T. Davinson; J. Eberth; A. Ekström; D. V. Fedorov; V. N. Fedosseev; L. M. Fraile; S. Franchoo; G. Georgiev; K. Gladnishki; M. Huyse; O. V. Ivanov; V. S. Ivanov; J. Iwanicki; J. Jolie; T. Konstantinopoulos; Th. Kröll; R. Krücken; U. Köster; A. Lagoyannis; G. Lo Bianco; P. Maierbeck; B. A. Marsh; P. Napiorkowski; N. Patronis; D. Pauwels; P. Reiter; M. Seliverstov; G. Sletten; J. Van de Walle; P. Van Duppen; D. Voulot; W. B. Walters; N. Warr; F. Wenander; K. Wrzosek

2010-10-13

202

Mission Overview. New Horizons is an exciting scientific investigation to obtain the first close look at  

E-print Network

Mission Overview. New Horizons is an exciting scientific investigation to obtain the first close) spectroscopy, radio science, and in situ plasma sensors. Scheduled for launch in 2006, New Horizons could fly-meter antenna Beacon Cruise Mode: Reduces risk REX PEPSSI LORRI PERSI SWAP SDC New Horizons on the Web

Stern, S. Alan

203

MLCT excited states and charge delocalization in some ruthenium/ ammine/polypyridyl complexes  

E-print Network

MLCT excited states and charge delocalization in some rutheniumÁ/ ammineÁ/polypyridyl complexes in simple ammineÁ/polypyridineÁ/ruthenium(II) complexes. A gaussian analysis of the absorption and emission Science B.V. Keywords: AmmineÁ/polypyridineÁ/ruthenium(II) complexes; Vertical MLCT energy; Metal

Schlegel, H. Bernhard

204

Pharmacology SchoolofMedicalSciences  

E-print Network

BSc (Hons) Immunology and Pharmacology Degree Programme Guide 2014-15 SchoolofMedicalSciences #12 and chronic inflammatory diseases. Immunology with pharmacology is therefore concerned primarily. The degree of Immunology & Pharmacology at Aberdeen is an exciting and original new programme which

Levi, Ran

205

BD BIOSCIENCES LIFE SCIENCE RESEARCH  

E-print Network

BD BIOSCIENCES LIFE SCIENCE RESEARCH BD FACSVantage SE Flow Cytometry System The Most Powerful fluorescence detector, third laser excitation spot, and CloneCytTM Plus with faster well-to-well access. We, width, and ratio of detector pulses. Pulse processing can be used to detect doublets in DNA analysis

Knowles, David William

206

2010 Neutron Review: ORNL Neutron Sciences Progress Report  

Microsoft Academic Search

During 2010, the Neutron Sciences Directorate focused on producing world-class science, while supporting the needs of the scientific community. As the instrument, sample environment, and data analysis tools at High Flux Isotope Reactor (HFIR ) and Spallation Neutron Source (SNS) have grown over the last year, so has promising neutron scattering research. This was an exciting year in science, technology,

Agatha A Bardoel; Deborah Melinda Counce; Allen E Ekkebus; Charlie M Horak; Stephen E Nagler; Lynn A Kszos

2011-01-01

207

Hedgehog Excitations and their Superconducting Cores in the Antiferromagnetic State of SO(5) Materials  

NASA Astrophysics Data System (ADS)

Zhang's SO(5) approach to the physics of high-temperature superconducting materials(S.-C. Zhang, Science 275), 1089 (1997). contains the possibility that the antiferromagnetic state should support novel excitations that resemble antiferromagnetic hedgehogs at large distances but are predominantly superconducting inside a core region(P. M. Goldbart, Antiferromagnetic hedgehogs with superconducting cores); cond- mat/9711088 (UIUC Preprint P-97-10-030-iii).. Neither singular nor topologically stable, in contrast with their hedgehog cousins in pure antiferromagnetism, these excitations are what hedgehogs become when antiferromagnetic order is permitted to `` escape'' toward superconductivity---a central element in Zhang's approach. We describe the structure of antiferromagnetic hedgehog excitations with superconducting cores within the context of Zhang's approach to high-temperature superconducting materials, and touch upon a number of the experimental implications that these excitations engender.

Goldbart, Paul M.

1998-03-01

208

Elementary excitations and crossover phenomenon in liquids.  

PubMed

The elementary excitations of vibration in solids are phonons. But in liquids phonons are extremely short lived and marginalized. In this Letter through classical and ab initio molecular dynamics simulations of the liquid state of various metallic systems we show that different excitations, the local configurational excitations in the atomic connectivity network, are the elementary excitations in high temperature metallic liquids. We also demonstrate that the competition between the configurational excitations and phonons determines the so-called crossover phenomenon in liquids. These discoveries open the way to the explanation of various complex phenomena in liquids, such as fragility and the rapid increase in viscosity toward the glass transition, in terms of these excitations. PMID:25167427

Iwashita, T; Nicholson, D M; Egami, T

2013-05-17

209

Elementary Excitations and Crossover Phenomenon in Liquids  

NASA Astrophysics Data System (ADS)

The elementary excitations of vibration in solids are phonons. But in liquids phonons are extremely short lived and marginalized. In this Letter through classical and ab initio molecular dynamics simulations of the liquid state of various metallic systems we show that different excitations, the local configurational excitations in the atomic connectivity network, are the elementary excitations in high temperature metallic liquids. We also demonstrate that the competition between the configurational excitations and phonons determines the so-called crossover phenomenon in liquids. These discoveries open the way to the explanation of various complex phenomena in liquids, such as fragility and the rapid increase in viscosity toward the glass transition, in terms of these excitations.

Iwashita, T.; Nicholson, D. M.; Egami, T.

2013-05-01

210

Accelerating structure with linear excitation  

SciTech Connect

The switched power linac (SPL) structures require a ring-shaped laser beam pulse of uniform intensity to avoid transverse field components of the accelerating field at the center. In order to also utilize the reflection of the outgoing EM wave, the switching element has to be very close to the outer edge of the structure to ensure nearly synchronous superposition at the beam hole with the original inward going wave. It is sometimes easier to produce linear (flat) laser beams, e.g., from powerful excimer lasers which have beams of rectangular cross section. Such flat beams could be used to excite linear photocathode switches or be used to produce flat electron beam pulses in electron sources. In this paper, an accelerator structure is proposed which may be considered a variant of the SPL disk structure, but could be used with linear beams. The structure utilizes a double parabolic horn. 8 refs., 9 figs.

Fischer, J.; Srinivasan-Rao, T.

1988-03-01

211

Excited Baryons in Holographic QCD  

SciTech Connect

The light-front holographic QCD approach is used to describe baryon spectroscopy and the systematics of nucleon transition form factors. Baryon spectroscopy and the excitation dynamics of nucleon resonances encoded in the nucleon transition form factors can provide fundamental insight into the strong-coupling dynamics of QCD. The transition from the hard-scattering perturbative domain to the non-perturbative region is sensitive to the detailed dynamics of confined quarks and gluons. Computations of such phenomena from first principles in QCD are clearly very challenging. The most successful theoretical approach thus far has been to quantize QCD on discrete lattices in Euclidean space-time; however, dynamical observables in Minkowski space-time, such as the time-like hadronic form factors are not amenable to Euclidean numerical lattice computations.

de Teramond, Guy F.; /Costa Rica U.; Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins

2011-11-08

212

Vibrationally Excited C4H  

NASA Astrophysics Data System (ADS)

Rotational spectra in four new excited vibrational levels of the linear carbon chain radical C4H were observed in the millimeter band between 69 and 364 GHz in a low pressure glow discharge, and two of these were observed in a supersonic molecular beam between 19 and 38 GHz. All have rotational constants within 0.4% of the {{X}2}{{{? }}+} ground vibrational state of C4H and were assigned to new bending vibrational levels, two each with 2{? } and 2{\\Pi } vibrational symmetry. The new levels are tentatively assigned to the 1{{? }6} and 1{{? }5} bending vibrational modes (both with 2{\\Pi } symmetry), and the 1{{? }6}+1{{? }7} and 1{{? }5}+1{{? }6} combination levels (2{? } symmetry) on the basis of the derived spectroscopic constants, relative intensities in our discharge source, and published laser spectroscopic and quantum calculations. Prior spectroscopic constants in the 1{{? }7} and 2{{? }7} levels were refined. Also presented are interferometric maps of the ground state and the 1{{? }7} level obtained with the Submillimeter Array (SMA) near 257 GHz which show that C4H is present near the central star in IRC+10216. We found no evidence with the SMA for the new vibrationally excited levels of C4H at a peak flux density averaged over a 3\\prime\\prime synthesized beam of ?slant 0.15 Jy/beam in the 294–296 and 304–306 GHz range, but it is anticipated that rotational lines in the new levels might be observed in IRC+10216 when ALMA attains its full design capability.

Cooksy, Andrew L.; Gottlieb, C. A.; Killian, T. C.; Thaddeus, P.; Patel, Nimesh A.; Young, Ken H.; McCarthy, M. C.

2015-02-01

213

131Cognitive Science COGNITIVE SCIENCE  

E-print Network

131Cognitive Science COGNITIVE SCIENCE PROFESSOR ELMES* MAJOR A major in cognitive science leading courses: Cognitive Science 110, 395, 403, 473; Computer Science 111, 211; Philosophy 106, 313; Psychology Science: Com- puter Science 295 (LISP, PROLOG or C), 313, 315; Psychology 207 b. Philosophical Foundations

Marsh, David

214

Quantal Density Functional Theory of Excited States  

SciTech Connect

We explain by quantal density functional theory the physics of mapping from any bound nondegenerate excited state of Schroedinger theory to an S system of noninteracting fermions with equivalent density and energy. The S system may be in a ground or excited state. In either case, the highest occupied eigenvalue is the negative of the ionization potential. We demonstrate this physics with examples. The theory further provides a new framework for calculations of atomic excited states including multiplet structure.

Sahni, Viraht; Massa, Lou; Singh, Ranbir; Slamet, Marlina

2001-09-10

215

Quantal density functional theory of excited states.  

PubMed

We explain by quantal density functional theory the physics of mapping from any bound nondegenerate excited state of Schrödinger theory to an S system of noninteracting fermions with equivalent density and energy. The S system may be in a ground or excited state. In either case, the highest occupied eigenvalue is the negative of the ionization potential. We demonstrate this physics with examples. The theory further provides a new framework for calculations of atomic excited states including multiplet structure. PMID:11531521

Sahni, V; Massa, L; Singh, R; Slamet, M

2001-09-10

216

Design evaluation: S-band exciters  

NASA Technical Reports Server (NTRS)

A design evaluation study was conducted to produce S-band exciter (SBE) system to provide a highly stable phase or modulated carrier for transmission to spacecraft. The exciter is part of an S-band receiver/exciter/ranging system at Spaceflight Tracking and Data Network (STDN) ground stations. The major features of the system are defined. Circuit diagrams of the electronic components are provided.

1974-01-01

217

Pi sigma* excited states in molecular photochemistry.  

PubMed

The last few years have seen a surge in interest (both theoretical and experimental) in the photochemistry of heteroaromatic molecules (e.g. azoles, phenols), which has served to highlight the importance of dissociative excited states formed by electron promotion to sigma* molecular orbitals. Such excited states--which, for brevity, are termed pi sigma* states in this Perspective article--may be populated by direct photo-excitation (though the transition cross-sections are intrinsically small), or indirectly, by non-adiabatic coupling from an optically 'bright' excited state (e.g. an excited state resulting from pi* <--pi excitation). The analogous pi sigma* excited states in prototypical hydride molecules like H(2)O and NH(3) have long been recognised. They have served as test-beds for developing concepts like Rydbergisation, conical intersections (CIs) between potential energy surfaces, and for investigating the ways in which non-adiabatic couplings at such CIs influence the eventual photofragmentation dynamics. This Perspective article seeks to highlight the continuity of behaviour revealed by the earlier small molecule studies and by the more recent studies of heteroaromatic systems, and to illustrate the photochemical importance of pi sigma* excited states in many broad families of molecules. Furthermore, the dynamical influence of such excited states is not restricted to closed shell species; the Article concludes with a brief consideration of the consequences of populating sigma* orbitals in free radical species, in molecular cations, and in dissociative electron attachment processes. PMID:20119599

Ashfold, Michael N R; King, Graeme A; Murdock, Daniel; Nix, Michael G D; Oliver, Thomas A A; Sage, Alan G

2010-02-14

218

Using photon to probe spin excitations  

NASA Astrophysics Data System (ADS)

Elementary spin excitations have attracted considerable attention in the understanding of strongly correlated materials, especially in high temperature superconductors where a full understanding of spin dynamics might reveal important information where the phase emerges in proximity of magnetic order. Photon spectroscopies, such as resonant inelastic x-ray scattering (RIXS) and optical Raman scattering, are powerful tools for the measurement of spin excitations. In this presentation, I will discuss the simulation of various spectroscopies that can reveal spin excitations, using both single- and multi-orbital models. I will show that transition metal in-direct RIXS provides information about two-magnon excitations at low energies in addition to the usual charge transfer excitations; while direct RIXS measures single spin-flip (single magnon) excitations, making it a complementary technique to inelastic neutron scattering. I also will show that Raman scattering can probe two-magnon spin excitations in correlated materials. We track the evolution of these excitations as functions of momentum and doping. These results highlight the nature of spin excitations in correlated materials and are an important step in our understanding of the corresponding experiments in real materials

Jia, Chunjing; Chen, Cheng-Chien Chen; Moritz, Brian; Devereaux, Tom

2013-03-01

219

Explore Science and Math Careers!  

NSDL National Science Digital Library

Science and math are important ingredients to some very exciting careers. Check out the videos below to see what could be in store for you! Architects use both science and math every day to design buildings, bridges, and many other structures. Have you ever wondered what an architect\\'s day is like? Look here: The civil engineer : a day in the life Because veterinarians use science to diagnose their animal patients and math to decide upon medications and treatments, they have to know about ...

M., Marcia

2005-05-11

220

NASA Science Served Family Style  

NASA Astrophysics Data System (ADS)

Family oriented innovative programs extend the reach of many traditional out-of-school venues to involve the entire family in learning in comfortable and fun environments. Research shows that parental involvement is key to increasing student achievement outcomes, and family-oriented programs have a direct impact on student performance. Because families have the greatest influence on children's attitudes towards education and career choices, we have developed a Family Science program that provides families a venue where they can explore the importance of science and technology in our daily lives by engaging in learning activities that change their perception and understanding of science. NASA Family Science Night strives to change the way that students and their families participate in science, within the program and beyond. After three years of pilot implementation and assessment, our evaluation data shows that Family Science Night participants have positive change in their attitudes and involvement in science.  Even after a single session, families are more likely to engage in external science-related activities and are increasingly excited about science in their everyday lives.  As we enter our dissemination phase, NASA Family Science Night will be compiling and releasing initial evaluation results, and providing facilitator training and online support resources. Support for NASA Family Science Nights is provided in part through NASA ROSES grant NNH06ZDA001N.

Noel-Storr, Jacob; Mitchell, S.; Drobnes, E.

2010-01-01

221

Science and Science Fiction  

SciTech Connect

I will explore the similarities and differences between the process of writing science fiction and the process of 'producing' science, specifically theoretical physics. What are the ground rules for introducing unproven new ideas in science fiction, and how do they differ from the corresponding rules in physics? How predictive is science fiction? (For that matter, how predictive is theoretical physics?) I will also contrast the way in which information is presented in science fiction, as opposed to its presentation in scientific papers, and I will examine the relative importance of ideas (as opposed to the importance of the way in which these ideas are presented). Finally, I will discuss whether a background as a research scientist provides any advantage in writing science fiction.

Scherrer, Robert (Vanderbilt University) [Vanderbilt University

2006-03-29

222

State preparation and excited electronic and vibrational behavior in hemes.  

PubMed

The temporally overlapping, ultrafast electronic and vibrational dynamics of a model five-coordinate, high-spin heme in a nominally isotropic solvent environment has been studied for the first time with three complementary ultrafast techniques: transient absorption, time-resolved resonance Raman Stokes, and time-resolved resonance Raman anti-Stokes spectroscopies. Vibrational dynamics associated with an evolving ground-state species dominate the observations. Excitation into the blue side of the Soret band led to very rapid S2 --> S1 decay (sub-100 fs), followed by somewhat slower (800 fs) S1 --> S0 nonradiative decay. The initial vibrationally excited, non-Boltzmann S0 state was modeled as shifted to lower energy by 300 cm(-1) and broadened by 20%. On a approximately 10 ps time scale, the S0 state evolved into its room-temperature, thermal distribution S0 profile largely through VER. Anti-Stokes signals disappear very rapidly, indicating that the vibrational energy redistributes internally in about 1-3 ps from the initial accepting modes associated with S1 --> S0 internal conversion to the rest of the macrocycle. Comparisons of anti-Stokes mode intensities and lifetimes from TRARRS studies in which the initial excited state was prepared by ligand photolysis [Mizutani, T.; Kitagawa, T. Science 1997, 278, 443, and Chem. Rec. 2001, 1, 258] suggest that, while transient absorption studies appear to be relatively insensitive to initial preparation of the electronic excited state, the subsequent vibrational dynamics are not. Direct, time-resolved evaluation of vibrational lifetimes provides insight into fast internal conversion in hemes and the pathways of subsequent vibrational energy flow in the ground state. The overall similarity of the model heme electronic dynamics to those of biological systems may be a sign that the protein's influence upon the dynamics of the heme active site is rather subtle. PMID:17020382

Challa, J Reddy; Gunaratne, Tissa C; Simpson, M Cather

2006-10-12

223

Science Mathematics Engineering  

E-print Network

Science Mathematics Engineering . ­ p.1 #12;Science Mathematics Engineering Science, Computer `Science', . ­ p.1 #12;Science Mathematics Engineering Science, Computer `Science', Mathematics, . ­ p.1 #12;Science Mathematics Engineering Science, Computer `Science', Mathematics, and Software Development

Hamlet, Richard

224

Excited-state wavepacket and potential reconstruction by coherent anti-Stokes Raman scattering.  

PubMed

Among the major challenges in the chemical sciences is controlling chemical reactions and deciphering their mechanisms. Since much of chemistry occurs in excited electronic states, in the last three decades scientists have employed a wide variety of experimental techniques and theoretical methods to recover excited-state potential energy surfaces and the wavepackets that evolve on them. These methods have been partially successful but generally do not provide a complete reconstruction of either the excited state wavepacket or potential. We have recently proposed a methodology for reconstructing excited-state molecular wavepackets and the corresponding potential energy surface [Avisar and Tannor, Phys. Rev. Lett., 2011, 106, 170405]. In our approach, the wavepacket is represented as a superposition of the set of vibrational eigenfunctions of the molecular ground-state Hamiltonian. We assume that the multidimensional ground-state potential surface is known, and therefore these vibrational eigenfunctions are known as well. The time-dependent coefficients of the basis functions are obtained by experimental measurement of the resonant coherent anti-Stokes Raman scattering (CARS) signal. Our reconstruction strategy has several significant advantages: (1) the methodology requires no a priori knowledge of any excited-state potential. (2) It applies to dissociative as well as to bound excited-state potentials. (3) It is general for polyatomics. (4) The excited-state potential surface is reconstructed simultaneously with the wavepacket. Apart from making a general contribution to the field of excited-state spectroscopy, our method provides the information on the excited-state wavepacket and potential necessary to design laser pulse sequences to control photochemical reactions. PMID:25119931

Avisar, David; Tannor, David J

2015-01-28

225

Connecting Science and Literacy in the Classroom: Using Space and Earth Science to Support Language Arts  

NASA Astrophysics Data System (ADS)

The connections between science and literacy in the classroom have received increasing attention over the last two decades, as more and more evidence demonstrates that science provides an exciting vehicle in which to engage students on the path to literacy improvement. Combining literacy with science allows students to creatively explore the world or universe, and it. Combining science and literacy improves both reading and science scores, and increases students’ interest in science. At a time when over 40% of students beyond the 5th grade are reading two or more levels below grade level and are struggling with their current materials, finding ways to excite and engage them in the reading process is key. Literacy programs incorporating unique space science content can help prepare children for standardized language arts tests. It also engages our nation’s youngest learners and their teachers with the science, math, and technology of exploration in a language arts format. This session focuses on programs and products that bring the excitement of earth and space science into the literacy classroom, with a focus on research-based approached to combining science and language arts. Reading, Writing and Rings! Grades 1-2

Wessen, A. S.; Cobabe-Ammann, E. A.

2009-12-01

226

Faculty of Science: EARTH SCIENCES  

E-print Network

Faculty of Science: EARTH SCIENCES Possible Careers Geologist Geochemist Geophysicist Mining - www.gac.ca Canadian Federation of Earth Sciences - www.geoscience.ca Canadian Geotechnical Society Engineer Glaciologist Science-Based Investment Advisor Environmental Consultant Land Surveyor Environmental

Brownstone, Rob

227

Quantal Density Functional Theory of Excited States  

Microsoft Academic Search

We explain by quantal density functional theory the physics of mapping from any bound nondegenerate excited state of Schrödinger theory to an S system of noninteracting fermions with equivalent density and energy. The S system may be in a ground or excited state. In either case, the highest occupied eigenvalue is the negative of the ionization potential. We demonstrate this

Viraht Sahni; Lou Massa; Ranbir Singh; Marlina Slamet

2001-01-01

228

Naphthalene in the higher triplet excited state.  

PubMed

Naphthalene in the higher triplet excited state Np(Tn) was generated from the two-step excitation method using two-colour two-laser flash photolysis technique and the lifetime of Np(Tn) was estimated to be 4.5 ps from the triplet energy quenching by quenchers such as p-dichlorobenzene, o-dicyanobenzene and carbon tetrachloride. PMID:12585401

Cai, Xichen; Hara, Michihiro; Kawai, Kiyohiko; Tojo, Sachiko; Majima, Tetsuro

2003-01-21

229

Study of excited nucleons and their structure  

SciTech Connect

Recent advances in the study of excited nucleons are discussed. Much of the progress has been achieved due to the availability of high precision meson production data in the photoproduction and electroproduction sectors, the development of multi-channel partial wave analysis techniques, and advances in Lattice QCD with predictions of the full excitation spectrum.

Burkert, Volker D. [JLAB, Newport News, VA (United States)

2014-01-01

230

What Gets a Cell Excited? Kinky Curves  

ERIC Educational Resources Information Center

Hodgkin and Huxley's (5) revealing the origins of cellular excitability is one of the great triumphs of physiology. In an extraordinarily deft series of papers, they were able to measure the essential electrical characteristics of neurons and synthesize them into a quantitative model that accounts for the excitability of neurons and other…

Kay, Alan R.

2014-01-01

231

Excitation Spectra of 1D Quantum Wires  

NASA Astrophysics Data System (ADS)

In this talk two different aspects of the excitation spectra of one dimensional (1D) semiconductor quantum wires will be discussed: (1) The nature of collective electronic excitations in 1D quantum wires; and (2) the band gap renormalization and excitonic effects in 1D quantum wires. In the first part, extensive theoretical results using the Bethe ansatz technique, the Lanczos' method, and the diagrammatic many-body theory will be presented for the spectral weight and the mode dispersion of the low-lying elementary electronic excitation spectra in 1D quantum wires with comparison to Raman Scattering experiments in GaAs quantum wires. Based on our detailed analytical and numerical results we conclude that the experimental observations are consistent with the existence of the collective charge density excitation mode, the collective spin density excitation mode, and a (low spectral weight) finite wave vector electron-hole single particle excitation mode (which arises from the finite curvature of the electron energy dispersion in the system). There is no evidence for a singlet spin density excitation mode in our calculations. In the second part, numerical solutions of the Bethe-Salpeter equation for interband excitonic transitions in 1D quantum wires will be presented. An approximate cancellation between self-energy and vertex correction effects is obtained in our calculations, providing an explaination for the experimental observation of an unshifted excitonic peak in highly excited 1D quantum wire lasers.

Wang, Daw-Wei

1998-03-01

232

Multiple parallel RF excited CO2 lasers  

Microsoft Academic Search

Dual waveguide lasers which are transversely excited in parallel from a common source of radio frequency are provided with one or more channels or bores connecting the laser cavities. The dimensions and configuration of the connecting channels are chosen so that the electric field from the applied RF excitation source will be higher in the connecting channels than in either

P. P. Chenauski; L. N. Laughman; E. H. Drinkwater

1985-01-01

233

Excitation equilibria in plasmas; a classification  

Microsoft Academic Search

This review gives a classification of the excitation kinetics ruled by electrons in plasmas. It is a study on the atomic state distribution function (ASDF) and its relation with underlying processes, which, for the case of an electron excitation kinetics (EEK) plasma, is merely a competition between free and bound electrons, the same particles in different circumstances. In a quasi

J. A. M. van der Mullen

1990-01-01

234

Elementary excitations and phase transitions in crystals  

SciTech Connect

The unique method of measuring elementary excitations in solids over a wide range of energy and momentum transfers is inelastic scattering of neutrons. Elementary excitations are defined as a correlated motion of atoms or spins in a solid which include phonons, magnons, rotons, or crystal field excitations. These excitations play a fundamental role in a wide variety of structural and magnetic phase transitions and provide the information in understanding the underlying microscopic mechanism of the transformation. Below, I shall review some of the relevant aspects of neutron scattering formalism related to inelastic neutron scattering and demonstrate how it has been applied to the study of phase transitions in crystals. I shall give two examples of structural phase transitions where the phonons are the elementary excitations and studies in a conventional superconductor where the phonon linewidths are a measure of the electron-phonon coupling responsible for the pairing.

Shapiro, S.M.

1993-12-31

235

Effects of core turbulence on jet excitability  

NASA Technical Reports Server (NTRS)

The effects of varying freestream core turbulence on the evolution of a circular jet with and without tonal excitation are examined. Measurements are made on an 8.8 cm diameter jet at a Mach number of 0.3. The jet is excited by plane waves at Strouhal number 0.5. For the excited and unexcited cases the turbulence level is varied by screens and grids placed upstream of the nozzle exit. The experiment results are compared with a theoretical model which incorporates a variable core turbulence and considers the energy interactions between the mean flow, the turbulence and the forced component. Both data and theory indicate that increasing the freestream turbulence diminishes the excitability of the jet and reduces the effect of excitation on the spreading rate of the jet.

Mankbadi, Reda R.; Rice, Edward J.; Raman, Ganesh

1989-01-01

236

Effects of core turbulence on jet excitability  

NASA Technical Reports Server (NTRS)

The effects of varying freestream core turbulence on the evolution of a circular jet with and without tonal excitation are examined. Measurements are made on an 8.8 cm diameter jet at a Mach number of 0.3. The jet is excitated by plane waves at Strouhal number 0.5. For the excited and unexcited cases the turbulence level is varied by screens and grids placed upstream of the nozzle exit. The experiment results are compared with a theoretical model which incorporates a variable core turbulence and considers the energy interactions between the mean flow, the turbulence and the forced component. Both data and theory indicate that increasing the freestream turbulence diminishes the excitability of the jet and reduces the effect of excitation on the spreading rate of the jet.

Mankbadi, Reda R.; Raman, Ganesh; Rice, Edward J.

1989-01-01

237

New Millennium Program: Servicing Earth and Space Sciences  

NASA Technical Reports Server (NTRS)

NASA has exciting plans for space science and Earth observations during the next decade. A broad range of advanced spacecraft and measurement technologies will be needed to support these plans within the existing budget and schedule constraints.

Li, F.

1999-01-01

238

1 Forensic Sciences FORENSIC SCIENCES  

E-print Network

1 Forensic Sciences FORENSIC SCIENCES As part of the Columbian College of Arts and Sciences' natural, mathematical and biomedical sciences programs, the forensic sciences program provides of the results. The Master of Forensic Sciences program offers the following concentrations: forensic chemistry

Vertes, Akos

239

Wine Science Wine Sciencee Science  

E-print Network

Wine Science Wine Sciencee Science Thomas Henick-Kling Professor of Enology Director of Viticulture & Enology Program #12;Wine Science Wine Science Growth of Washington Wine Industry #12;Wine Science Wine Science Wine Grapes utilized 2007 2008 2009 2010 WA 127,000 145,000 156,000 160,000 NY 24,000 26,000 30

240

Science Sampler: Making movies in the classroom  

NSDL National Science Digital Library

When you overhear students talking excitedly about video games, the internet, television, or movies, do you ever wish that they could get that excited about what was happening in the science classroom? By using simple software, students can plan, shoot, and edit movies of their own design! In this fascinating activity, students create a documentary on a famous earthquake, volcanic eruption, tsunami, hurricane, or other natural disaster as they put their own unique spin on the theory of plate tectonics.

Lauren Richards

2006-07-01

241

Two-photon excitation fluorescence microscopy and its application in functional connectomics.  

PubMed

Two-photon excitation fluorescence microscopy has become widely used in various life science fields in this decade. In the field of neuroscience in particular, in vivo two-photon microscopy has provided vital information on neural activity and brain function. In the current era of connectomics, visualization of the morphology and activity of numerous neurons in ever larger regions of the living brain are required within short periods. Based on this viewpoint, we discuss the fundamentals, advantages and potential of two-photon excitation fluorescence microscopy for the investigation of neural circuit functions. PMID:25540030

Nemoto, Tomomi; Kawakami, Ryosuke; Hibi, Terumasa; Iijima, Koichiro; Otomo, Kohei

2015-02-01

242

Setting the Scene: Basic Rules for a Safer Science Classroom  

NSDL National Science Digital Library

Six classes, six teachers--just navigating middle school is a voyage of discovery for early adolescents. We offer them a confusing array of choices, many in science. Sometimes it seems we spend too much science class time teaching organization, caution, and control. But these skills--critical to making science experiences exciting and safe--are also important science processes. This free selection includes the Table of Contents, Foreword, Introduction, and References.

Texley, Juliana; Kwan, Terry

2003-01-01

243

Hydrogen Bonding in the Electronic Excited State  

NASA Astrophysics Data System (ADS)

Here, I will give a talk on our recent advances in electronic excited-state hydrogen-bonding dynamics and the significant role of excited-state hydrogen bonding on internal conversion (IC), electronic spectral shifts (ESS), photoinduced electron transfer (PET), fluorescence quenching (FQ), intramolecular charge transfer (ICT), and metal-to-ligand charge transfer (MLCT). The combination of various spectroscopic experiments with theoretical calculations has led to tremendous progress in excited-state hydrogen-bonding research. We first demonstrated that intermolecular hydrogen bond in excited state can be greatly strengthened or weakened for many chromophores. We have also clarified that intermolecular hydrogen-bond strengthening and weakening correspond to red-shifts and blue-shifts, respectively, in the electronic spectra. Moreover, radiationless deactivations (via IC, PET, ICT, MLCT, and so on) can be dramatically influenced by excited-state hydrogen bonding. References: [1] Guang-Jiu Zhao, and Ke-Li Han, Hydrogen Bonding in the Electronic Excited State, Accounts of Chemical Research 45, 404--413 (2012). http://pubs.acs.org/doi/pdf/10.1021/ar200135h [2] Book: Hydrogen Bonding and Transfer in the Excited State, Editors: Ke-Li Han and Guang-Jiu Zhao, ISBN: 978-0-470-66677-7, John Wiley & Sons Ltd, Chichester, UK (2011). http://onlinelibrary.wiley.com/book/10.1002/9780470669143

Zhao, Guang-Jiu; Han, Ke-Li

2013-03-01

244

FT-Kaman Spectroscopy And Pulsed Excitation  

NASA Astrophysics Data System (ADS)

It has been previously shown that equivalent results are obtained in FT-Raman spectroscopy using both pulsed and CW excitation if the following two criteria are met. 1) The pulse repetition rate must be significantly higher than the detector roll-off, and 2) The pulse length must be long enough so that interferometer resolution is not degraded. The results using a mode locked Nd/YAG laser operated with various pulse widths will be shown. The operation with pulsed excitation is necessary if one wishes to do a pump-probe Raman experiment for the detection of excited state Raman spectra. The initial results of such an experiment will be shown.

Chase, Bruce D.; Gustafson, Terry L.

1989-12-01

245

Seismic excitation by space shuttles  

USGS Publications Warehouse

Shock waves generated by the space shuttles Columbia (August 13, 1989), Atlantis (April 11, 1991) and Discovery (September 18, 1991) on their return to Edwards Air Force Base, California, were recorded by TERRAscope (Caltech's broadband seismic network), the Caltech-U.S.G.S Southern California Seismic Network (SCSN), and the University of Southern California (USC) Los Angeles Basin Seismic Network. The spatial pattern of the arrival times exhibits hyperbolic shock fronts from which the path, velocity and altitude of the space shuttle could be determined. The shock wave was acoustically coupled to the ground, converted to a seismic wave, and recorded clearly at the broadband TERRAscope stations. The acoustic coupling occurred very differently depending on the conditions of the Earth's surface surrounding the station. For a seismic station located on hard bedrock, the shock wave (N wave) was clearly recorded with little distortion. Aside from the N wave, very little acoustic coupling of the shock wave energy to the ground occurred at these sites. The observed N wave record was used to estimate the overpressure of the shock wave accurately; a pressure change of 0.5 to 2.2 mbars was obtained. For a seismic station located close to the ocean or soft sedimentary basins, a significant amount of shock wave energy was transferred to the ground through acoustic coupling of the shock wave and the oceanic Rayleigh wave. A distinct topography such as a mountain range was found effective to couple the shock wave energy to the ground. Shock wave energy was also coupled to the ground very effectively through large man made structures such as high rise buildings and offshore oil drilling platforms. For the space shuttle Columbia, in particular, a distinct pulse having a period of about 2 to 3 seconds was observed, 12.5 s before the shock wave, with a broadband seismograph in Pasadena. This pulse was probably excited by the high rise buildings in downtown Los Angeles which were simultaneously hit by the space shuttle shock waves. The proximity of the natural periods of the high rise buildings and the modal periods of the Los Angeles basin enabled efficient energy transfer from shock wave to seismic wave. ?? 1992 Springer-Verlag.

Kanamori, H.; Mori, J.; Sturtevant, B.; Anderson, D.L.; Heaton, T.

1992-01-01

246

MULTISCALE RECONSTRUCTION FOR PHOTON-LIMITED SHIFTED EXCITATION RAMAN SPECTROSCOPY  

E-print Network

MULTISCALE RECONSTRUCTION FOR PHOTON-LIMITED SHIFTED EXCITATION RAMAN SPECTROSCOPY Rebecca Willett excitation Raman spectroscopy results in multiple ob- servations of the sum of a material's fluorescent frequen- cies. The technique, known as Shifted Excitation Raman Difference Spectroscopy (SERDS

Willett, Rebecca

247

Students Excited by Stellar Discovery  

NASA Astrophysics Data System (ADS)

In the constellation of Ophiuchus, above the disk of our Milky Way Galaxy, there lurks a stellar corpse spinning 30 times per second -- an exotic star known as a radio pulsar. This object was unknown until it was discovered last week by three high school students. These students are part of the Pulsar Search Collaboratory (PSC) project, run by the National Radio Astronomy Observatory (NRAO) in Green Bank, WV, and West Virginia University (WVU). The pulsar, which may be a rare kind of neutron star called a recycled pulsar, was discovered independently by Virginia students Alexander Snider and Casey Thompson, on January 20, and a day later by Kentucky student Hannah Mabry. "Every day, I told myself, 'I have to find a pulsar. I better find a pulsar before this class ends,'" said Mabry. When she actually made the discovery, she could barely contain her excitement. "I started screaming and jumping up and down." Thompson was similarly expressive. "After three years of searching, I hadn't found a single thing," he said, "but when I did, I threw my hands up in the air and said, 'Yes!'." Snider said, "It actually feels really neat to be the first person to ever see something like that. It's an uplifting feeling." As part of the PSC, the students analyze real data from NRAO's Robert C. Byrd Green Bank Telescope (GBT) to find pulsars. The students' teachers -- Debra Edwards of Sherando High School, Leah Lorton of James River High School, and Jennifer Carter of Rowan County Senior High School -- all introduced the PSC in their classes, and interested students formed teams to continue the work. Even before the discovery, Mabry simply enjoyed the search. "It just feels like you're actually doing something," she said. "It's a good feeling." Once the pulsar candidate was reported to NRAO, Project Director Rachel Rosen took a look and agreed with the young scientists. A followup observing session was scheduled on the GBT. Snider and Mabry traveled to West Virginia to assist in the follow-up observations, and Thompson joined online. "Observing with the students is very exciting. It gives the students a chance to learn about radio telescopes and pulsar observing in a very hands-on way, and it is extra fun when we find a pulsar," said Rosen. Snider, on the other hand, said, "I got very, very nervous. I expected when I went there that I would just be watching other people do things, and then I actually go to sit down at the controls. I definitely didn't want to mess something up." Everything went well, and the observations confirmed that the students had found an exotic pulsar. "I learned more in the two hours in the control room than I would have in school the whole day," Mabry said. Pulsars are spinning neutron stars that sling lighthouse beams of radio waves or light around as they spin. A neutron star is what is left after a massive star explodes at the end of its normal life. With no nuclear fuel left to produce energy to offset the stellar remnant's weight, its material is compressed to extreme densities. The pressure squeezes together most of its protons and electrons to form neutrons; hence, the name neutron star. One tablespoon of material from a pulsar would weigh 10 million tons -- as much as a supertanker. The object that the students discovered is in a special class of pulsar that spins very fast - in this case, about 30 times per second, comparable to the speed of a kitchen blender. "The big question we need to answer first is whether this is a young pulsar or a recycled pulsar," said Maura McLaughlin, an astronomer at WVU. "A pulsar spinning that fast is very interesting as it could be newly born or it could be a very old, recycled pulsar." A recycled pulsar is one that was once in a binary system. Material from the companion star is deposited onto the pulsar, causing it to speed up, or be recycled. Mystery remains, however, about whether this pulsar has ever had a companion star. If it did, "it may be t

2011-02-01

248

Fear, excitement, and financial risk-taking.  

PubMed

Can fear trigger risk-taking? In this paper, we assess whether fear can be reinterpreted as a state of excitement as a result of contextual cues and promote, rather than discourage, risk-taking. In a laboratory experiment, the participants' emotional states were induced (fear vs. control), followed by a purportedly unrelated financial task. The task was framed as either a stock market investment or an exciting casino game. Our results showed that incidental fear (vs. control) induced risk-averse behaviour when the task was framed as a stock investment decision. However, fear encouraged risk-taking when the very same task was framed as an exciting casino game. The impact of fear on risk-taking was partially mediated by the excitement felt during the financial task. PMID:24661027

Lee, Chan Jean; Andrade, Eduardo B

2015-01-01

249

Mode Selective Excitation Using Coherent Control Spectroscopy  

SciTech Connect

Femtosecond time-resolved coherent anti-Stokes Raman scattering (fs-CARS) gives access to ultrafast molecular dynamics. However, femtosecond laser pulses are spectrally broad and therefore coherently excite several molecular modes. While the temporal resolution is high, usually no mode-selective excitation is possible. This paper demonstrates the feasibility of selectively exciting specific molecular vibrations in solution phase with shaped fs laser excitation using a feedback-controlled optimization technique guided by an evolutionary algorithm. This approach is also used to obtain molecule-specific CARS spectra from a mixture of different substances. The optimized phase structures of the fs pulses are characterized to get insight into the control process. Possible applications of the spectrum control are discussed.

Singh, Ajay K. [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai-400094 (India); School of Engineering and Science, Jacobs University Bremen, Bremen, 28759 (Germany); Konradi, Jakow; Materny, Arnulf [School of Engineering and Science, Jacobs University Bremen, Bremen, 28759 (Germany); Sarkar, Sisir K. [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai-400094 (India)

2008-11-14

250

Stable Manifolds as Thresholds for Multipulse Excitability  

E-print Network

)], Electrodynamic convection in liquid crystals [Peacock et al, J. Fluid Mech. 432 (2001)], Food chains in predator, Nonlinearity 18 (2005), 1095-1120.] PA/BK/HO - Stable manifolds and excitability ­ p. #12;Menu for today

Doedel, Eusebius

251

Detecting cracked rotors using auxiliary harmonic excitation  

NASA Astrophysics Data System (ADS)

Cracked rotors are not only important from a practical and economic viewpoint, they also exhibit interesting dynamics. This paper investigates the modelling and analysis of machines with breathing cracks, which open and close due to the self-weight of the rotor, producing a parametric excitation. After reviewing the modelling of cracked rotors, the paper analyses the use of auxiliary excitation of the shaft, often implemented using active magnetic bearings to detect cracks. Applying a sinusoidal excitation generates response frequencies that are combinations of the rotor spin speed and excitation frequency. Previously this system was analysed using multiple scales analysis; this paper suggests an alternative approach based on the harmonic balance method, and validates this approach using simulated and experimental results. Consideration is also given to some issues to enable this approach to become a robust condition monitoring technique for cracked shafts.

Sawicki, Jerzy T.; Friswell, Michael I.; Kulesza, Zbigniew; Wroblewski, Adam; Lekki, John D.

2011-03-01

252

Acoustics of Excited Jets: A Historical Perspective  

NASA Technical Reports Server (NTRS)

The idea that a jet may be excited by external forcing is not new. The first published demonstration of a jet responding to external pressure waves occurred in the mid-1800's. It was not, however, until the 1950's, with the advent of commercial jet aircraft, that interest in the subject greatly increased. Researchers first used excited jets to study the structure of the jet and attempt to determine the nature of the noise sources. The jet actuators of the time limited the range (Reynolds and Mach numbers) of jets that could be excited. As the actuators improved, more realistic jets could be studied. This has led to a better understanding of how jet excitation may be used not only as a research tool to understand the flow properties and noise generation process, but also as a method to control jet noise.

Brown, Cliffard A.

2005-01-01

253

Inclination Excitation in Extrasolar Planetary Systems  

NASA Astrophysics Data System (ADS)

The Kepler Mission has detected dozens of planetary systems with more than four transiting planets. This sample provides a collection of planetary systems with little or no excited inclination between the inferred orbits. This present study examines the magnitude and efficacy of three potential mechanisms for exciting orbital inclination in these systems: self-excitation of orbital inclination in initially coplanar planetary systems, perturbations by larger bodies within the planetary systems, and perturbations by massive bodies external to the systems. For each of these mechanisms, we determine the regime(s) of parameter space for which orbital inclination excitation is effective. This work provides constraints on the properties (masses and orbital elements) of possible additional bodies in observed planetery systems, and on their dynamical history. One interesting application is to consider the relative size of the external perturbations both in and out of clusters.

Becker, Juliette; Adams, Fred C.

2015-01-01

254

Editor's Corner: Small Science  

NSDL National Science Digital Library

We know that nanotechnology offers real possibilities. It already appears in commercial products such as computers, sunscreens, high-performance sporting equipment, and stain-resistant fabrics. The evolution from vacuum tubes to transistors and high-density integrated circuits has transformed the modern world. Nature itself has shown the way to nanoscale engineering, with molecule-sized assembly lines such as ribosomes and DNA polymerase. Clearly, this "small science" has huge possibilities! The Field Editor discusses the exciting world of nanotechnology in this month's Editor's Corner column.

2006-12-01

255

Computer Science  

NSDL National Science Digital Library

Computer science is the study of computational systems and their use in representing important problems in science and society. Major topics include computational science, software systems, network systems, theory of computation, machine learning, and human-computer interaction.

K-12 Outreach,

256

The Synchronous Generator Digital Excitation Regulator  

Microsoft Academic Search

This paper introduces the theory and the trait that the digital excitation used on the medium and small generator. The corn of the adjuster is Atmel89C52 singlechip. The adjuster adopts digital adjusting ,PID(Proportion Integration Differentiation) control arithmetic. It has many merits, such as briefness and trustiness, lower cost, good expansion capability and so on. By experimental testify, this excitation adjuster

Ma Linlin; Wang Bing

2010-01-01

257

Stellar Pulsations excited by a scattered mass  

E-print Network

We compute the energy spectra of the gravitational signals emitted when a mass m is scattered by the gravitational field of a star of mass M >> m. We show that, unlike black holes in similar processes, the quasi-normal modes of the star are excited, and that the amount of energy emitted in these modes depends on how close the exciting mass can get to the star.

V. Ferrari; L. Gualtieri; A. Borrelli

1999-01-22

258

Care of the patient in excited delirium.  

PubMed

Patients with excited delirium present a challenge to both law enforcement and health care personnel because handcuffs, the traditional method used to keep persons from harming themselves and others, may be fatal. The patient's survival depends upon rapid recognition and treatment, including chemical sedation, decreased environmental stimulation, intravenous fluids, and other supportive interventions. Excited delirium protocols should be established to ensure rapid and appropriate treatment to ensure patient survival and the safety of those caring for them. PMID:22766142

Gordon, Cheryl; Schmelzer, Marilee

2013-03-01

259

Evolution of locally excited avalanches in semiconductors  

E-print Network

We show that semiconductor avalanche photodiodes can exhibit diminutive amplification noise during the early evolution of avalanches. The noise is so low that the number of locally excited charges that seed each avalanche can be resolved. These findings constitute an important first step towards realization of a solid-state noiseless amplifier. Moreover, we believe that the experimental setup used, \\textit{i.e.}, time-resolving locally excited avalanches, will become a useful tool for optimizing the number resolution.

Z. L. Yuan; J. F. Dynes; A. W. Sharpe; A. J. Shields

2010-03-03

260

FORENSIC SCIENCE About Forensic Science  

E-print Network

Fact Sheet FORENSIC SCIENCE About Forensic Science: The Forensic Science program at SJSU offers: The SJSU Forensic Science program delivers coursework and training to · Empowergraduatestobecomeagentsofchangetorecognize, document and report errors and injustices in the practice of forensic science and crime scene

Su, Xiao

261

1 Political Science POLITICAL SCIENCE  

E-print Network

1 Political Science POLITICAL SCIENCE With Capitol Hill nearby and the White House just blocks away, GW is the ideal place to study political science. Students in the program benefit from rigorous study and behavioral sciences discipline in the Columbian College of Arts and Sciences, the program examines politics

Vertes, Akos

262

Earth Sciences Environmental Earth Sciences,  

E-print Network

94 Earth Sciences­ Environmental Earth Sciences, Geology Degree options MGeol (Single Honours Degrees) Earth Sciences BSc (Single Honours Degrees) Environmental Earth Sciences Geology BSc (Joint placement. * The Geology and Environmental Earth Sciences degrees are accredited by the Geological Society

Brierley, Andrew

263

Asymptotic properties of mathematical models of excitability  

E-print Network

, R. Suckley2 , V. N. Biktashev2, 1 Department of Computer Science, University of Liverpool, Liverpool L69 3BX, UK and 2 Department of Mathematical Sciences, University of Liverpool, Liverpool L69 7ZL

Biktashev, Vadim N.

264

Asymptotic properties of mathematical models of excitability  

E-print Network

2 , R. Suckley 2 , V. N. Biktashev 2,# 1 Department of Computer Science, University of Liverpool, Liverpool L69 3BX, UK and 2 Department of Mathematical Sciences, University of Liverpool, Liverpool L69 7ZL

Biktashev, Vadim N.

265

Multiscale Dynamical Framework for High-Level Calculations of Finite Temperature Ground and Excited State Properties  

SciTech Connect

There is a pressing need for accurate calculation of finite temperature ground and excited state properties of nanoscale systems relevant to structural biology, hydrogen economy, environmental and material science problems. To address this challenging task we have designed a multiscale dynamical approach that combines the accuracy and computational complexity of coupled-cluster (CC) methods with the efficiency of classical molecular dynamics simulations. Our methodology is based on a seamless integration between the generic QM/MM interface, Tensor Contraction Engine module, and the classical molecular dynamics module of NWChem and offers an unprecedented ability for accurate large scale calculations of thermodynamics of ground and excited state properties. We illustrate our approach by large scale dynamical simulation of excited state spectrum of the cytosine base in its native DNA environment using variant of the completely renormalized equation-of-motion method with singles, doubles, and non-iterative triples (CR-EOMCCSD(T)).

Kowalski, Karol; Valiev, Marat

2006-06-25

266

Multiscale dynamical framework for high-level calculations of finite temperature ground and excited state properties  

NASA Astrophysics Data System (ADS)

There is a pressing need for accurate calculations of finite temperature ground and excited state properties of nanoscale systems relevant to structural biology, hydrogen economy, environmental and material science problems. To address this challenging task we have designed a multiscale dynamical approach that combines the accuracy and computational complexity of coupled-cluster (CC) methods with the efficiency of classical molecular dynamics simulations. Our methodology is based on a seamless integration between the generic QM/MM interface, Tensor Contraction Engine module, and the classical molecular dynamics module of NWChem and offers an unprecedented ability for accurate large scale calculations of thermodynamics of ground and excited state properties. We illustrate our approach by large scale dynamical simulation of the excited state spectrum of the cytosine base in its native DNA environment using a variant of the completely renormalized equation-of-motion method with singles, doubles, and non-iterative triples (CR-EOMCCSD(T)).

Kowalski, Karol; Valiev, Marat

2006-09-01

267

Temporal focusing with spatially modulated excitation.  

PubMed

Temporal focusing of ultrashort pulses has been shown to enable wide-field depth-resolved two-photon fluorescence microscopy. In this process, an entire plane in the sample is selectively excited by introduction of geometrical dispersion to an ultrashort pulse. Many applications, such as multiphoton lithography, uncaging or region-of-interest imaging, require, however, illumination patterns which significantly differ from homogeneous excitation of an entire plane in the sample. Here we consider the effects of such spatial modulation of a temporally focused excitation pattern on both the generated excitation pattern and on its axial confinement. The transition in the axial response between line illumination and wide-field illumination is characterized both theoretically and experimentally. For 2D patterning, we show that in the case of amplitude-only modulation the axial response is generally similar to that of wide-field illumination, while for phase-and-amplitude modulation the axial response slightly deteriorates when the phase variation is rapid, a regime which is shown to be relevant to excitation by beams shaped using spatial light modulators. Finally, general guidelines for the use of spatially modulated temporally focused excitation are presented. PMID:19333304

Papagiakoumou, Eirini; de Sars, Vincent; Emiliani, Valentina; Oron, Dan

2009-03-30

268

Atmospheric excitation of nonseasonal polar motion  

NASA Technical Reports Server (NTRS)

Analysis of nonseasonal polar motion excitation and atmospheric mass equatorial angular momentum (EAM) over land for the period 1980-1989 reveals a clear pattern of high power and correlation during the northern hemisphere (NH) winter followed by low power and correlation during the NH summer. A special case of this pattern occurs for longer than 14 months (from January 1987 to March 1988) when the correlation throughout the NH summer remains statistically significant. During this epoch an average of 72% of the nonseasonal polar motion excitation power at frequencies between -30 and +12 cycles/yr linearly related to atmospheric EAM over land. During the southern hemisphere winter there is significant correlation between the atmospheric EAM over midlatitude southern oceans and polar motion excitation indicating the existence of a dynamic atmosphere-ocean excitation. The atmospheric excitation power is too small to explain the large correlation during the NH winter. The effects of winds probably account for the deficit in power. The implication of these results is that there are two main excitation sources each dominant at different seasons. Atmospheric mass redistribution over land forces polar motion during the NH winter, and a dynamic atmpshere-ocean response is important during the SH winter.

Kuehne, John; Johnson, Stuart; Wilson, Clark R.

1993-01-01

269

Förster excitation energy transfer in peridinin-chlorophyll-a-protein.  

PubMed Central

Time-resolved fluorescence anisotropy spectroscopy has been used to study the chlorophyll a (Chl a) to Chl a excitation energy transfer in the water-soluble peridinin-chlorophyll a-protein (PCP) of the dinoflagellate Amphidinium carterae. Monomeric PCP binds eight peridinins and two Chl a. The trimeric structure of PCP, resolved at 2 A (, Science. 272:1788-1791), allows accurate calculations of energy transfer times by use of the Förster equation. The anisotropy decay time constants of 6.8 +/- 0.8 ps (tau(1)) and 350 +/- 15 ps (tau(2)) are respectively assigned to intra- and intermonomeric excitation equilibration times. Using the ratio tau(1)/tau(2) and the amplitude of the anisotropy, the best fit of the experimental data is achieved when the Q(y) transition dipole moment is rotated by 2-7 degrees with respect to the y axis in the plane of the Chl a molecule. In contrast to the conclusion of, Biochemistry. 23:1564-1571) that the refractive index (n) in the Förster equation should be equal to that of the solvent, n can be estimated to be 1.6 +/- 0.1, which is larger than that of the solvent (water). Based on our observations we predict that the relatively slow intermonomeric energy transfer in vivo is overruled by faster energy transfer from a PCP monomer to, e.g., the light-harvesting a/c complex. PMID:10620298

Kleima, F J; Hofmann, E; Gobets, B; van Stokkum, I H; van Grondelle, R; Diederichs, K; van Amerongen, H

2000-01-01

270

Communicating Science  

NASA Astrophysics Data System (ADS)

Introduction: what this book is about and why you might want to read it; Prologue: three orphans share a common paternity: professional science communication, popular journalism, and literary fiction are not as separate as they seem; Part I. Professional Science Communication: 1. Spreading the word: the endless struggle to publish professional science; 2. Walk like an Egyptian: the alien feeling of professional science writing; 3. The future's bright? Professional science communication in the age of the internet; 4. Counting the horse's teeth: professional standards in science's barter economy; 5. Separating the wheat from the chaff: peer review on trial; Part II. Science for the Public: What Science Do People Need and How Might They Get It?: 6. The Public Understanding of Science (PUS) movement and its problems; 7. Public engagement with science and technology (PEST): fine principle, difficult practice; 8. Citizen scientists? Democratic input into science policy; 9. Teaching and learning science in schools: implications for popular science communication; Part III. Popular Science Communication: The Press and Broadcasting: 10. What every scientist should know about mass media; 11. What every scientist should know about journalists; 12. The influence of new media; 13. How the media represents science; 14. How should science journalists behave?; Part IV. The Origins of Science in Cultural Context: Five Historic Dramas: 15. A terrible storm in Wittenberg: natural knowledge through sorcery and evil; 16. A terrible storm in the Mediterranean: controlling nature with white magic and religion; 17. Thieving magpies: the subtle art of false projecting; 18. Foolish virtuosi: natural philosophy emerges as a distinct discipline but many cannot take it seriously; 19. Is scientific knowledge 'true' or should it just be 'truthfully' deployed?; Part V. Science in Literature: 20. Science and the Gothic: the three big nineteenth-century monster stories; 21. Science fiction: serious literature of ideas or low-grade entertainment?; 22. Science in British literary fiction; 23. Science on stage: the politics and ethics of science in cultural and educational contexts.

Russell, Nicholas

2009-10-01

271

FOREWORD Nanomaterials science Nanomaterials science  

NASA Astrophysics Data System (ADS)

The nanometer regime covers the transition from condensed matter behavior to atomic and molecular properties and thus is a very rich but also very demanding area in materials science. Close to the condensed matter side, properties and functions might still very well be scalable, whereas close to the atomic and molecular side, the scalability is mostly lost. Properties and functions change qualitatively or quantitatively by orders of magnitude when the dimensions become smaller than a critical size in the nanometer range. Examples are the ballistic regime for electron or spin transport at dimensions below the mean free path, near-field effects in scanning near-field optical microscopy and quantum wells when the dimensions are below an appropriate wavelength, novel electronic, mechanical, and chemical properties when the number of bulk atoms becomes smaller than that of surface atoms, quantum conduction, and Coulomb blockade. Thus, by going below a certain size, an abundance of novel properties and functions are at one's disposal, or, in other words, we can functionalize materials simply by reducing their size to the nanoscale. The key to the future lies in the functions that we give to materials, not just in finding 'novel functional materials'. This catch expression in many materials science programs and initiatives of the past two decades sounds great, but it is not what really counts. All materials are functional in one way or another and, therefore, all new materials are 'novel functional materials'. Certainly, finding new materials is always an important part of progress, but we should also focus on the much larger domain of novel functions that we can give to existing or modified materials. A good example is semiconductors: they are fifty or more years old and their properties are very well known, but they were not of widespread interest and use until the transistor changed their destiny into being the central material in the information technology revolution. Interfaces gave them their functions, and shaping them into ever-smaller functional components made them indispensably omnipresent as transistors—produced in billions per person and per year—and they are no doubt the rulers of today's technical world. The semiconductor and transistor serve as an inspiring example of functionalizing materials. The developments of microelectronics profited very much from scalability, that is, the properties and functions do not change significantly with size. Therefore, every step toward smaller dimensions was a technical and commercial challenge with risks well under control. The transition to the nanoscale, however, is discontinuous. Examples of this transition are the local probe methods that exploit the mechanically controlled proximity to the object under consideration and that have become indispensable as microscopes and as measuring and modifying tools, the size of molecular components that are much smaller than the smallest possibly achievable transistor, the properties and functions of materials below a critical size as mentioned above, the continuum properties versus discrete ones, and novel concepts inspired by living nature. Those novel concepts include growing circuits first and building the active components at the nodes afterwards and measuring weak by weak, small by small, and many by many. It is these discontinuous steps that make the nanoscale different, not just smaller. They pose exciting challenges, open great opportunities and nearly unlimited possibilities, but they also carry serious technical, commercial, environmental, and health risks. The nanoscale is also a great opportunity for materials science in general. Materials science is interdisciplinary per se. A materials scientist should have a reasonable understanding of physics, chemistry, engineering, and more recently, also biology. Certainly one can always team up with representatives from other disciplines and forge collaborations. However, an effective team can only emerge from a common understanding of the respective languages and problems. Th

Rohrer, Heinrich

2010-10-01

272

Crop Science Investigation (CSI) Network  

NSDL National Science Digital Library

Crop Science Investigation (CSI) Network        This site is designed to serve as a clearinghouse of lesson plans and other materials useful for teaching 4-H and FFA youth about crop and soil sciences.  Check out this site for information to use in your classroom, workshops, or 4-H meetings.       As youth become less connected with agriculture, it is essential to teach them about agriculture. A series of workshops, called Crop Science Investigation or CSI was created to help spark the interest of youth to learn about crops and plants.Dig into some interesting facts about Nebraska crops.Learn how crops grow and factors that affect them.Learn about exciting career opportunities related to crop and plant science. The University of Nebraska offers great majors for anyone interested in anything plants!  Check it out!

273

CLSI: Cool Life Science Investigations  

NSDL National Science Digital Library

With the number of popular medical and forensics programs on television and many references in the media today, even elementary students can comfortably throw around terms such as cells, DNA, and artificial products. However, their questions on these topics often go unanswered, or they are left with misinformation regarding these concepts. As a result, a group of university science educators and the resource coordinator for an elementary school gifted program teemed up to create accurate, developmentally appropriate, and exciting experiences with these topics for students in grades K-5. The result of this collaborative effort was an after-school science "tradeshow," which is described here.

Falsarella, Carell; Marek, Edmund A.; Mccann, Florence F.; Pederson, Jon E.

2007-12-01

274

Visionlearning: The Process of Science  

NSDL National Science Digital Library

This classroom-tested instructional unit was developed to build interest and excitement about the practice of science by real people in real laboratories. It takes learners on a journey to understand how a good experiment is designed, how to recognize bias and error, how to perform an investigation into the natural world, and how to clearly communicate about the findings. It is divided into 15 sections, many of which can be parsed out separately. Topics include scientific ethics, funding for science, research methods, data analysis/interpretation, statistics, error and uncertainty, the peer review process, and understanding scientific articles.

2010-09-30

275

Earth Sciences Division annual report 1989  

SciTech Connect

This Annual Report presents summaries of selected representative research activities from Lawrence Berkeley Laboratory grouped according to the principal disciplines of the Earth Sciences Division: Reservoir Engineering and Hydrology, Geology and Geochemistry, and Geophysics and Geomechanics. We are proud to be able to bring you this report, which we hope will convey not only a description of the Division's scientific activities but also a sense of the enthusiasm and excitement present today in the Earth Sciences.

Not Available

1990-06-01

276

Science Signaling Podcast: 06 May 2008  

NSDL National Science Digital Library

This conversation is about research highlighted in Editors' Choice titled, "What’s So Exciting About Glia?" The highlighted article is R. Káradóttir, N. B. Hamilton, Y. Bakiri, D. Attwell, Spiking and nonspiking classes of oligodendrocyte precursor glia in CNS white matter. Nat. Neurosci. 11, 450–456 (2008). (Length: 6 min; file size: 2.61 MB; file format: mp3; location: http://podcasts.aaas.org/science_signaling/ScienceSignaling_080506.mp3)

Elizabeth M. Adler (American Association for the Advancement of Science;Science Signaling REV); Annalisa M. VanHook (American Association for the Advancement of Science;Science Signaling REV)

2008-05-06

277

Terahertz excitations in the 1D Ising chain quantum magnet CoNb2O6  

NASA Astrophysics Data System (ADS)

The one-dimensional magnet CoNb2O6 was recently demonstrated to be an excellent realization of a one-dimensional quantum Ising spin chain. It has been shown to undergo a quantum phase transition in a magnetic field oriented transverse to its ferromagnetically aligned spin chains. Low energy spin-flip excitations in the chains were recently observed via inelastic neutron scattering.ootnotetextR. Coldea, et al, Science 327, 177 (2010) The energy spectrum of these excitations was shown to have a interesting energy scaling governed by symmetries of the E8 exceptional Lie group. Here, time-domain terahertz spectroscopy (TDTS) is used to investigate optically active low energy excitations in CoNb2O6. We take advantage of the polarization sensitivity of this technique to characterize both electric and magnetic dipole active excitations in this compound. A connection is made from the q=0 response observed here to the excitations observed by neutron scattering. In addition, we will show preliminary data on the terahertz spectra of this material as it undergoes the magnetic field-tuned quantum phase transition.

Morris, Christopher M.; Valdés Aguilar, R.; Koopayeh, S.; Broholm, C.; Armitage, N. P.

2012-02-01

278

Science Matters  

ERIC Educational Resources Information Center

The spaces and structures used for undergraduate science often work against new teaching methods and fail to provide environments that attract the brightest students to science. The undergraduate science building often offers little to inspire the imaginations of young minds. The typical undergraduate science building also tends to work against…

Odell, Bill

2005-01-01

279

Science Magazine  

NSDL National Science Digital Library

Science Magazine is published by the American Association for the Advancement of Science (AAAS) and serves its readers as a forum for the presentation and discussion of important issues related to the advancement of science. The gopher site contains the current issue's table of contents, editorial, "This Week in SCIENCE" column, plus the classified ads and information for contributors.

1995-01-01

280

Some Aspects of the Current Revolution in the Earth Sciences  

ERIC Educational Resources Information Center

Summarizes the present state of sea-floor spreading theory, elaborates upon some apparent consequences,and makes some suggestions about future education in the earth sciences. The author concludes that the future of the earth sciences looks bright and exciting. (RR)

Wilson, J. Tuzo

1969-01-01

281

"Celebrate Science" Has Formula for Hands-On Learning  

ERIC Educational Resources Information Center

Cost-effective, easily replicated program is a win-win situation for high schoolers who teach science and for their elementary students. The thank-you letter from Leslie, a grade-schooler in San Diego County's Ramona Unified School District, speaks volumes about the excitement generated by "Celebrate Science"--an innovative, standards-based…

Brydolf, Carol

2012-01-01

282

Stability of excited atoms in small cavities  

NASA Astrophysics Data System (ADS)

We consider a system consisting of an atom in the approximation of a harmonic oscillator of frequency ?bar, coupled to the scalar potential inside a spherical reflecting cavity of radius R. We use dressed states introduced in a previous publication [Andion, Malbouisson, and Mattos Neto, J. Phys. A 34, 3735 (2001)], which allow a nonperturbative unified description of the atom radiation process, in both cases, of a finite or an arbitrarily large cavity. We perform a study of the energy distribution in a small cavity, with the initial condition that the atom is in the first excited state and we conclude for the quasi-stability of the excited atom. For instance, for a frequency ?bar of the order ?bar~4.00×1014/s (in the visible red), starting from the initial condition that the atom is in the first excited level, we find that for a cavity with diameter 2R~1.0×10-6 m, the probability of the atom being at any time still in the first excited level, will be of the order of 97%. For a typical microwave frequency ?bar~2.00×1010/s we find stability in the first excited state also of the order of 97% for a cavity radius R~1.4×10-2 m.

Flores-Hidalgo, G.; Malbouisson, A. P.; Milla, Y. W.

2002-06-01

283

The Exciting Wavelength of Extended Red Emission  

NASA Astrophysics Data System (ADS)

We propose to determine the wavelength of the photons which excite Extended Red Emission {ERE} by mapping the small scale structure of ERE and molecular hydrogen {H_2} in the reflection nebulae NGC 2023 and 7023. Both of these nebulae display sharp narrow ERE-filaments within photodissociation regions {PDR} which also show infrared H_2 fluorescence. In these opically thick filaments, different wavelength photons penetrate to different depths. By comparing the widths of these filaments in ERE and H_2 we will determine the exciting wavelength of ERE. This is possible because the combined opacity of dust and H_2 to the exciting radiation {lambda < 1100 A} of H_2 fluorescence is known, and the comparison of the thickness of the ERE and H_2 filaments will allow a determination of the dust opacity at the wavelength at which ERE is being excited. This is a sensitive test to distinguish between different materials which have been proposed as the carrier of ERE {e.g., carbon or silicon nanoparticles, polycyclic aromatic hydrocarbon molecules, hydrogenated amorphous carbon, etc.}, because the photoluminescense excitation spectra of these different materials differ by large amounts. Identifying the material which produces ERE is important as recent work on ERE in the diffuse interstellar medium has shown that the material which produces ERE comprises a significant component of dust grains.

Gordon, Karl

2003-07-01

284

Targeting individual excited states in DMRG.  

NASA Astrophysics Data System (ADS)

The low-lying excited states of ?-conjugated molecules are important for the development of novel devices such as lasers, light-emitting diodes, photovoltaic cells, and field-effect transistors [1,2]. The ab-intio Density Matrix Renormalization Group (DMRG) provides a powerful way to explore the electronic structure of quasi-one-dimensional systems such as conjugated organic oligomers. However, DMRG is limited to targeting only low-lying excited states through state-averaged DMRG (SDMRG). There are several drawbacks; state-averaging degrades the accuracy of the excited states and is limited to at most a few of the low-lying states [3]. In this study, we present a new method for targeting higher individual excited states. Due to progress in the field of numerical analysis presented by Van Der Horst and others [4], we are able to target individual excited states of the Hamiltonian. This is accomplished by modifying the Jacobi-Davidson algorithm via a ``Harmonic Ritz'' procedure. We will present studies of oligoacenes and polyenes that compare the accuracy of SDMRG and Harmonic Davidson DMRG. [1] Burroughes, et al. , Nature 347, 539 (1990). [2] Shirota, J. Mater. Chem. 10, 1, (2000). [3] Ramasesha, Pati, Krishnamurthy, Shuai, Bredas, Phys. Rev. B. 54, 7598, (1997). [4] Bai, Demmel, Dongarra, Ruhe, Van Der Horst, Templates for the Solution of Algebraic Eigenvalue Problems, SIAM, 2000.

Dorando, Jonathan; Hachmann, Johannes; Kin-Lic Chan, Garnet

2007-03-01

285

Tone-excited jet: Theory and experiments  

NASA Technical Reports Server (NTRS)

A detailed study to understand the phenomenon of broadband jet-noise amplification produced by upstream discrete-tone sound excitation has been carried out. This has been achieved by simultaneous acquisition of the acoustic, mean velocity, turbulence intensities, and instability-wave pressure data. A 5.08 cm diameter jet has been tested for this purpose under static and also flight-simulation conditions. An open-jet wind tunnel has been used to simulate the flight effects. Limited data on heated jets have also been obtained. To improve the physical understanding of the flow modifications brought about by the upstream discrete-tone excitation, ensemble-averaged schlieren photographs of the jets have also been taken. Parallel to the experimental study, a mathematical model of the processes that lead to broadband-noise amplification by upstream tones has been developed. Excitation of large-scale turbulence by upstream tones is first calculated. A model to predict the changes in small-scale turbulence is then developed. By numerically integrating the resultant set of equations, the enhanced small-scale turbulence distribution in a jet under various excitation conditions is obtained. The resulting changes in small-scale turbulence have been attributed to broadband amplification of jet noise. Excellent agreement has been found between the theory and the experiments. It has also shown that the relative velocity effects are the same for the excited and the unexcited jets.

Ahuja, K. K.; Lepicovsky, J.; Tam, C. K. W.; Morris, P. J.; Burrin, R. H.

1982-01-01

286

Bridging Science and Policy: The AGU Science Policy Conference  

NASA Astrophysics Data System (ADS)

In recent years, science has become inextricably linked to the political process. As such, it is more important now than ever for science to forge a better relationship with politics, for the health of both science and society. To help meet this need, the American Geophysical Union (AGU) strives to engage its members, shape policy, and inform society about the excitement of Earth and space science and its role in developing solutions for the sustainability of the planet. In June 2013, AGU held its second annual Science Policy Conference in Washington, D.C. The goal of the conference is to provide a new forum for diverse discussions and viewpoints on the challenges and opportunities of science policy, with a focus on applications of Earth and space science that serve local, national, and international communities. The meeting brought together more than 300 scientists, policy makers, industry professionals, members of the press, and other stakeholders to discuss the topics concerning the Arctic, climate change, oceans, energy, technology and infrastructure, and natural hazards science as they relate to challenges impacting society. Sessions such as 'The Water-Energy Nexus,' 'Potential for Megadisasters,' 'The Changing Ocean and Impacts on Human Health,' and 'Drowning and Drought: Agricultural Impacts of Climate Change' are examples of some of the intriguing and timely science policy issues addressed at the conference. The findings from the conference were used to develop a summary report. The report highlights key facts and figures to be used as a resource in discussions with policy makers and other stakeholders regarding the conference topics. This presentation will discuss the goals and outcomes of the conference and how the event represents one of the many ways AGU is approaching its 'Science and Society' priority objective as part of the Union's strategic plan; namely by increasing the effectiveness and recognition of AGU among policy makers as an authoritative source of integrated, interdisciplinary Earth and space science information.

Hankin, E. R.; Uhlenbrock, K.; Landau, E. A.

2013-12-01

287

Science Shorts: Spoilage Science  

NSDL National Science Digital Library

Whether it's fresh or processed, all food eventually spoils. Methods such as freezing, canning, and the use of preservatives lengthen the lifespan of foods, and we--and the modern food industry--rely on these methods to maintain our food supply. This month's Science Shorts explores the concepts of food spoilage and prevention.

2005-01-01

288

Soapy Science. Teaching Science.  

ERIC Educational Resources Information Center

Describes a science and math activity that involves bubbles, shapes, colors, and solid geometry. Students build geometric shapes with soda straws and submerge the shapes in soapy water, allowing them to review basic geometry concepts, test hypotheses, and learn about other concepts such as diffraction, interference colors, and evaporation. (TJQ)

Leyden, Michael

1997-01-01

289

Science Playwiths  

NSDL National Science Digital Library

Science Playwiths consists of a set of small experiments using simple everyday science, selected for quick, easy use by K-6 teachers. Topics include Earth science, physics, electricity and magnetism, fluid flow, sound, light, and others. There is also a set of more complex experiments, methods and enquiries; an Australian science and technology timeline; a set of ideas for science projects and some help; and "The Ugly Islands", a simulation exercise that offers problems for people to play with.

Macinnis, Peter

290

Excited light meson spectroscopy from lattice QCD  

SciTech Connect

I report on recent progress in calculating excited meson spectra using lattice QCD, emphasizing results and phenomenology. With novel techniques we can now extract extensive spectra of excited mesons with high statistical precision, including spin-four states and those with exotic quantum numbers. As well as isovector meson spectra, I will present new calculations of the spectrum of excited light isoscalar mesons, something that has up to now been a challenge for lattice QCD. I show determinations of the flavor content of these mesons, including the eta-eta' mixing angle, providing a window on annihilation dynamics in QCD. I will also discuss recent work on using lattice QCD to map out the energy-dependent phase shift in pi-pi scattering and future applications of the methodology to the study of resonances and decays.

Christopher Thomas, Hadron Spectrum Collaboration

2012-04-01

291

Shear layer excitation, experiment versus theory  

NASA Technical Reports Server (NTRS)

The acoustical excitation of shear layers is investigated. Acoustical excitation causes the so-called orderly structures in shear layers and jets. Also, the deviations in the spreading rate between different shear layer experiments are due to the same excitation mechanism. Measurements in the linear interaction region close to the edge from which the shear layer is shed are examined. Two sets of experiments (Houston 1981 and Berlin 1983/84) are discussed. The measurements were carried out with shear layers in air using hot wire anemometers and microphones. The agreement between these measurements and the theory is good. Even details of the fluctuating flow field correspond to theoretical predictions, such as the local occurrence of negative phase speeds.

Bechert, D. W.; Stahl, B.

1984-01-01

292

Ultrasoft fermionic excitation at finite chemical potential  

NASA Astrophysics Data System (ADS)

It has been suggested previously that an ultrasoft fermionic excitation develops, albeit with a small spectral weight, in a system of massless fermions and scalar bosons with Yukawa interaction at high temperature T. In this paper we study how this excitation is modified at finite chemical potential ?. We relate the existence of the ultrasoft mode to symmetries, in particular charge conjugation, and a supersymmetry of the free system which is spontaneously broken by finite temperature and finite density effects, as argued earlier by Lebedev and Smilga. A nonvanishing chemical potential breaks both symmetries explicitly and maximally at zero temperature where the mode ceases to exist. A detailed calculation indicates that the ultrasoft excitation persists as long as T?0.71?.

Blaizot, Jean-Paul; Satow, Daisuke

2014-05-01

293

BLAIR'S "CONDENSER THEORY" OF NERVE EXCITATION.  

PubMed

Blair's recent theory of excitation is analysed with the following conclusions: 1. The theory is inapplicable to currents of long duration; i.e., slowly increasing currents and the opening excitation. 2. The theory is a modification of the condenser theory of excitation but the modification is to be rejected on three grounds: (a) The modification has no obvious physical significance. (b) It does not in fact remedy the divergence between calculation and observation. (c) It leads to certain conclusions of a surprising kind which are contrary to observed fact. 3. The qualitative value of the condenser theory is demonstrated by the fairly close agreement between calculation and observation over a considerable field of enquiry. PMID:19872794

Rushton, W A

1934-01-20

294

Collective excitations in itinerant spiral magnets  

NASA Astrophysics Data System (ADS)

We investigate the coupled charge and spin collective excitations in the spiral phases of the two-dimensional Hubbard model using a generalized random-phase approximation. Already for small doping the spin-wave excitations are strongly renormalized due to low-energy particle-hole excitations. Besides the three Goldstone modes of the spiral state the dynamical susceptibility reveals an extra zero mode for low doping and strong coupling values signaling an intrinsic instability of the homogeneous spiral state. In addition, near-zero modes are found in the vicinity of the spiral pitch wave number for out-of-plane spin fluctuations. Their origin is found to be the near degeneracy with staggered noncoplanar spiral states which, however, are not the lowest energy Hartree-Fock solutions among the homogeneous spiral states.

Kampf, A. P.

1996-01-01

295

CENTRE FOR SCIENCE EDUCATION SCIENCE AND TECHNOLOGY  

E-print Network

FOR SCIENCE EDUCATION SCIENCE AND TECHNOLOGY AARHUS UNIVERSITY 13 JUNE 2013 Project work CENTRE FOR SCIENCE EDUCATION SCIENCE AND TECHNOLOGY AARHUS UNIVERSITY 13 JUNE audio-visual element #12; CENTRE FOR SCIENCE EDUCATION SCIENCE AND TECHNOLOGY AARHUS

296

[Faculty of Science Information and Computing Sciences  

E-print Network

[Faculty of Science Information and Computing Sciences] Terminating combinator parsers in Agda and Computing Sciences Utrecht University June 12, 2008 #12;[Faculty of Science Information and Computing Sciences] 2 Overview Totality Parser combinators Terminating combinator parsers #12;[Faculty of Science

Löh, Andres

297

The photodissociation and reaction dynamics of vibrationally excited molecules  

SciTech Connect

We have used combined vibrational overtone excitation and laser induced fluorescence detection to study dissociation dynamics of hydroxylamine (NH[sub 2]OH), have performed our first laser induced grating experiments on water, and have begun assembling a new apparatus for preparing vibrationally excited molecules with simulated Raman excitation. We study role of vibrational excitation in photodissociation dynamics by using a vibrational state preparation technique, such as vibrational overtone excitation or stimulated Raman excitation, to create molecules with particular nuclear motions and then to excite that molecule to a dissociative electronic state.

Not Available

1993-01-01

298

Faculty of Science General Science  

E-print Network

, chemistry and biochemistry, computer science, earth and environmental sciences, mathematics, physics Science degree, then add specialized technical lab skills with a one- or two-year college program. #12-year, general degree in science can fulfill requirements to proceed to further professional training in health

299

Natural Sciences Tripos EARTH SCIENCES  

E-print Network

Natural Sciences Tripos EARTH SCIENCES University of Cambridge Undergraduate Prospectus 2013.indd 1Undergraduate Prospectus 2013.indd 1 29/07/2013 16:44:3529/07/2013 16:44:35 #12;Department of Earth Sciences is the science of the Earth. What is the Earth made of? What processes shape and change it? What's happened

Cambridge, University of

300

Faculty of Science Computer Science  

E-print Network

Faculty of Science Computer Science Software engineering, network and system analysis continue a variety of computer science programs to prepare students for a career in the technology industry or in research and academia. A computer science degree provides an in-depth understanding of the fundamentals

301

Faculty of Science Computer Science  

E-print Network

Faculty of Science Computer Science Computer software engineering, network and system analysis.uwindsor.ca/computerscience The University of Windsor offers a variety of computer science programs to prepare students for a career in the technology industry or in research and academia. A computer science degree provides an in-depth understanding

302

Earth Sciences Environmental Earth Sciences,  

E-print Network

84 Earth Sciences­ Environmental Earth Sciences, Geology MGeol (Single Honours Degrees) Earth Sciences BSc (Single Honours Degrees) Environmental Earth Sciences Geology BSc (Joint Honours Degrees) and among the most research-intensive in Europe. Features * The Department of Earth and Environmental

Brierley, Andrew

303

BROADBAND EXCITATION IN NUCLEAR MAGNETIC RESONANCE  

SciTech Connect

Theoretical methods for designing sequences of radio frequency (rf) radiation pulses for broadband excitation of spin systems in nuclear magnetic resonance (NMR) are described. The sequences excite spins uniformly over large ranges of resonant frequencies arising from static magnetic field inhomogeneity, chemical shift differences, or spin couplings, or over large ranges of rf field amplitudes. Specific sequences for creating a population inversion or transverse magnetization are derived and demonstrated experimentally in liquid and solid state NMR. One approach to broadband excitation is based on principles of coherent averaging theory. A general formalism for deriving pulse sequences is given, along with computational methods for specific cases. This approach leads to sequences that produce strictly constant transformations of a spin system. The importance of this feature in NMR applications is discussed. A second approach to broadband excitation makes use of iterative schemes, i.e. sets of operations that are applied repetitively to a given initial pulse sequences, generating a series of increasingly complex sequences with increasingly desirable properties. A general mathematical framework for analyzing iterative schemes is developed. An iterative scheme is treated as a function that acts on a space of operators corresponding to the transformations produced by all possible pulse sequences. The fixed points of the function and the stability of the fixed points are shown to determine the essential behavior of the scheme. Iterative schemes for broadband population inversion are treated in detail. Algebraic and numerical methods for performing the mathematical analysis are presented. Two additional topics are treated. The first is the construction of sequences for uniform excitation of double-quantum coherence and for uniform polarization transfer over a range of spin couplings. Double-quantum excitation sequences are demonstrated in a liquid crystal system. The second additional topic is the construction of iterative schemes for narrowband population inversion. The use of sequences that invert spin populations only over a narrow range of rf field amplitudes to spatially localize NMR signals in an rf field gradient is discussed.

Tycko, R.

1984-10-01

304

Communicating Science through Exhibitions  

NASA Astrophysics Data System (ADS)

It is critically important for the public to better understand the scientific process. Museum exhibitions are an important part of informal science education that can effectively reach public audiences as well as school groups. They provide an important gateway for the public to learn about compelling scientific endeavors. Science exhibitions also provide a marvelous opportunity for scientists to become engaged in the exhibit development process. The Space Science Institute (SSI) is a national leader in producing traveling science exhibitions and their associated educational programming (i.e. interactive websites, educator workshops, public talks, instructional materials). The focus of this presentation will be on two of its exhibit projects: MarsQuest (on tour for four years) and Alien Earths (its tour began early in 2005). MarsQuest is enabling millions of Americans to share in the excitement of the scientific exploration of Mars and to learn more about their own planet in the process. Alien Earths will bring origins-related research and discoveries to students and the American public. It has four interrelated exhibit areas: Our Place in Space, Star Birth, Planet Quest, and Search for Life. Exhibit visitors will explore the awesome events surrounding the birth of stars and planets; they will join scientists in the hunt for planets outside our solar system including those that may be in ``habitable zones'' around other stars; and finally they will be able to learn about how scientists are looking for signs of life beyond Earth. SSI is also developing interactive web sites based on exhibit themes. New technologies are transforming the Web from a static medium to an interactive environment with tremendous potential for informal education and inquiry-based investigations. This talk will focus on the role informal science projects play in effectively communicating science to a broad, public audience.

Dusenbery, Paul

2005-04-01

305

Faculty of Science & Health SCHOOL OF NURSING  

E-print Network

Faculty of Science & Health SCHOOL OF NURSING Lecturer in Mental Health Nursing (5 year contract university based School of Nursing that is closely associated with a number of partner health services. This is a very exciting time in the development of nursing practice, nursing research and education in Ireland

Humphrys, Mark

306

Science Teaching to Fire the Imagination.  

ERIC Educational Resources Information Center

Presents a range of exciting ideas for encouraging active learning, for illuminating new concepts, and for making science lessons fun. Topics include modeling, matter, heat, diffusion, changes of state, heat transfer, energy changes, atomic structure, waves, gravity, enzymes, and habitats. (JRH)

Sandford, Diana; Fleetwood, Julie

1997-01-01

307

Safer Science: Building Safety in Foreign Language  

NSDL National Science Digital Library

A school is about to undergo major renovations and new construction to handle a growing student population. So some science classes and labs are assigned to other parts of the building temporarily. Most teachers are excited about the opportunity to help d

Roy, Ken

2011-01-01

308

Exciting Baryons: now and in the future  

SciTech Connect

This is the final talk of NSTAR2011 conference. It is not a summary talk, but rather a looking forward to what still needs to be done in excited baryon physics. In particular, we need to hone our tools connecting experimental inputs with QCD. At present we rely on models that often have doubtful connections with the underlying theory, and this needs to be dramatically improved, if we are to reach definitive conclusions about the relevant degrees of freedom of excited baryons. Conclusions that we want to have by NSTAR2021.

Michael Pennington

2012-04-01

309

Charmonium excited state spectrum in lattice QCD  

SciTech Connect

Working with a large basis of covariant derivative-based meson interpolating fields we demonstrate the feasibility of reliably extracting multiple excited states using a variational method. The study is performed on quenched anisotropic lattices with clover quarks at the charm mass. We demonstrate how a knowledge of the continuum limit of a lattice interpolating field can give additional spin-assignment information, even at a single lattice spacing, via the overlap factors of interpolating field and state. Excited state masses are systematically high with respect to quark potential model predictions and, where they exist, experimental states. We conclude that this is most likely a result of the quenched approximation.

Jozef Dudek; Robert Edwards; Nilmani Mathur; David Richards

2008-02-01

310

Stretched-State Excitations with the  

Microsoft Academic Search

Neutron time-of-fight spectra were obtained for the ^{14}C(p,n) ^{14}N, ^{18 }O(p,n)^{18}F, and ^{30}Si(p,n) ^{30}P reactions at 135 MeV with the beam-swinger system at the Indiana University Cyclotron Facility. Excitation-energy spectra and the differential cross sections for the observed excitations in these reactions were extracted over the momentum transfer range from 0 to 2.7 fm^{-1}. The primary goal of this work

Luis Alberto Casimiro Garcia

1992-01-01

311

Gluonic excitations in the hadronic spectrum  

SciTech Connect

QCD at low energy features a gluonic field that is strongly coupled to itself and to quarks. I will present a summary of what we know about the role that excitations of the gluonic field play in determining the spectrum of meson resonances. Recent studies using lattice techniques have suggested a phenomenology of gluonic excitations within QCD that leads to hybrid mesons with both exotic and non-exotic quantum numbers. I will discuss these calculations and describe their relationship to current experimental knowledge and to forthcoming experiments at Jefferson Lab and elsewhere.

Dudek, Jozef J. [ODU, JLAB

2014-06-01

312

Increased Excitability of Acidified Skeletal Muscle  

PubMed Central

Generation of the action potentials (AP) necessary to activate skeletal muscle fibers requires that inward membrane currents exceed outward currents and thereby depolarize the fibers to the voltage threshold for AP generation. Excitability therefore depends on both excitatory Na+ currents and inhibitory K+ and Cl? currents. During intensive exercise, active muscle loses K+ and extracellular K+ ([K+]o) increases. Since high [K+]o leads to depolarization and ensuing inactivation of voltage-gated Na+ channels and loss of excitability in isolated muscles, exercise-induced loss of K+ is likely to reduce muscle excitability and thereby contribute to muscle fatigue in vivo. Intensive exercise, however, also leads to muscle acidification, which recently was shown to recover excitability in isolated K+-depressed muscles of the rat. Here we show that in rat soleus muscles at 11 mM K+, the almost complete recovery of compound action potentials and force with muscle acidification (CO2 changed from 5 to 24%) was associated with reduced chloride conductance (1731 ± 151 to 938 ± 64 ?S/cm2, P < 0.01) but not with changes in potassium conductance (405 ± 20 to 455 ± 30 ?S/cm2, P < 0.16). Furthermore, acidification reduced the rheobase current by 26% at 4 mM K+ and increased the number of excitable fibers at elevated [K+]o. At 11 mM K+ and normal pH, a recovery of excitability and force similar to the observations with muscle acidification could be induced by reducing extracellular Cl? or by blocking the major muscle Cl? channel, ClC-1, with 30 ?M 9-AC. It is concluded that recovery of excitability in K+-depressed muscles induced by muscle acidification is related to reduction in the inhibitory Cl? currents, possibly through inhibition of ClC-1 channels, and acidosis thereby reduces the Na+ current needed to generate and propagate an AP. Thus short term regulation of Cl? channels is important for maintenance of excitability in working muscle. PMID:15684096

Pedersen, Thomas H.; de Paoli, Frank; Nielsen, Ole B.

2005-01-01

313

Female reproductive steroids and neuronal excitability.  

PubMed

Oestrogen and progesterone have specific receptors in the central nervous system and are able to regulate neuronal development and plasticity, neuronal excitability, mitochondrial energy production, and neurotransmitter synthesis, release, and transport. On neuronal excitability, estradiol and progesterone seem to have an opposite effect, with estradiol being excitatory and progesterone and its derivative allopregnanolone being inhibitory. Estradiol augments N-methyl-D-aspartate-mediated glutamate receptor activity, while progesterone enhances gamma-aminobutyric acid-mediated chloride conductance. Sex steroid regulation of the balance of neuroexcitatory and neuroinhibitory activities may have a role in modulating clinical susceptibility to different neurological conditions such as migraine, catamenial epilepsy, premenstrual dysphoric disorder, and premenstrual syndrome. PMID:21533709

Finocchi, C; Ferrari, M

2011-05-01

314

Bogoliubov Excited States and the Lyth Bound  

E-print Network

We show that Bogoliubov excited scalar and tensor modes do not alleviate Planckian evolution during inflation if one assumes that $r$ and the Bogoliubov coefficients are approximately scale invariant. We constrain the excitation parameter for the scalar fluctuations, $\\beta$, and tensor perturbations, $\\tilde{\\beta}$, by requiring that there be at least three decades of scale invariance in the scalar and tensor power spectrum. For the scalar fluctuations this is motivated by the observed nearly scale invariant scalar power spectrum. For the tensor fluctuations this assumption may be shown to be valid or invalid by future experiments.

Aditya Aravind; Dustin Lorshbough; Sonia Paban

2014-08-07

315

Laser pulses for coherent xuv Raman excitation  

E-print Network

We combine multi-channel electronic structure theory with quantum optimal control to derive Raman pulse sequences that coherently populate a valence excited state. For a neon atom, Raman target populations of up to 13% are obtained. Superpositions of the ground and valence Raman states with a controllable relative phase are found to be reachable with up to 4.5% population and phase control facilitated by the pump pulse carrier envelope phase. Our results open a route to creating core-hole excitations in molecules and aggregates that locally address specific atoms and represent the first step towards realization of multidimensional spectroscopy in the xuv and x-ray regimes.

Greenman, Loren; Whaley, K Birgitta

2014-01-01

316

TeraGrid Gateways for Earth Science  

NASA Astrophysics Data System (ADS)

The increasingly digital component of science today poses exciting challenges and opportunities for researchers. Whether it's streaming data from sensors to computations, tagging video in the study of language patterns or the use of geographic information systems to anticipate the spread of disease, the challenges are enormous and continue to grow. The existence of advanced cyberinfrastructure (CI) tools or science gateways can significantly increase the productivity of researchers facing the most difficult challenges - in some cases making the impossible possible. The TeraGrid Science Gateways program works to incorporate high end resources through these community-designed interfaces. This talk will present an overview of TeraGrid's gateway program and highlight several gateways in atmospheric science, earth sciences and geography and regional science, geophysics, global atmospheric research, materials research and seismology.

Wilkins-Diehr, Nancy

2010-05-01

317

Inquiry: The Key to Exemplary Science  

NSDL National Science Digital Library

Science teachers aiming to foster inquiry in their classrooms will find the sixth title in the Exemplary Science monograph series, Inquiry: The Key to Exemplary Science full of helpful advice and new techniques. The 18 chapters in this monograph illustrate various forms of inquiry, offer detailed examples of planning and execution, and provide case studies highlighting successful implementation of inquiry. Student learning, development of positive attitudes, the ability to use concepts and skills in completely new situations are all demonstrated for use in your classroom. The National Science Education Standards call "for every student (every year) to experience the richness and excitement of knowing and understanding the natural world." Editor Robert Yager notes that "in one sense, inquiry can be used as a synonym for science. Both include starting with questions, collecting evidence concerning the explanations offered, and arguing with others about the validity of the explanations. Science is a continuing quest for better understanding of the natural universe. This quest is inquiry!

2009-04-01

318

Science Standards  

NSDL National Science Digital Library

The Asia-Pacific Economic Cooperation (APEC) has created a Web site that offers English translations of the academic standards of Asian countries. This is a good way to compare U.S. science standards to Asian and Asia Pacific countries. Science standards are typically organized into three content areas: Earth and space sciences, life sciences, and physical sciences. Standards may also develop desired abilities or performance skill strands such as conceptual understanding, theorizing and analyzing, solving problems, communicating, and using tools, processes and procedures. This site allows for comparison of science standards between Australia, Japan, Korea, Malaysia, New Zealand, Singapore, Chinese Taipei, and the United States.

2009-08-13

319

COMPUTER SCIENCE INFORMATION TECHNOLOGY  

E-print Network

COMPUTER SCIENCE and INFORMATION TECHNOLOGY POSTGRADUATE STUDIES 2006 School of Mathematics of Information Systems with Honours Master of Science (Computer Science) Professional Doctorate in Science (Computer Science) PhD (Computer Science) The postgraduate programs in Computer Science and Information

Dunstan, Neil

320

New Logic Circuit with DC Parametric Excitation  

NASA Astrophysics Data System (ADS)

It is shown that dc parametric excitation is possible in a circuit named JUDO, which is composed of two resistively-connected Josephson junctions. Simulation study proves that the circuit has large gain and properties suitable for the construction of small, high-speed logic circuits.

Sugahara, Masanori; Kaneda, Hisayoshi

1982-12-01

321

Fragment emission from modestly excited nuclear systems  

Microsoft Academic Search

Fragment emission patterns occurring in nuclear systems of modest excitation are studied. Exclusive measurement of fragment emission in 14N+197Au reactions at EA = 100, 130 and 156 MeV allows selection of central collisions where a single source dominates the decay. Low threshold measurement of IMF emission for these events allows investigation of the influence of detector threshold effects. The time

Y. Lou; R. T. de Souza; S. L. Chen; E. W. Cornell; B. Davin; D. Fox; T. M. Hamilton; K. McDonald; M. B. Tsang; T. Glasmacher; J. Dinius; C. K. Gelbke; D. O. Handzy; W. C. Hsi; M. Huang; W. G. Lynch; C. Montoya; C. Schwarz; D. Prindle; A. A. Sonzogni; R. Vandenbosch; J. L. Wile; M. Parker; C. L. Coffing

1996-01-01

322

A new mixed excitation LPC vocoder  

Microsoft Academic Search

The authors introduce a novel synthesizer structure for an LPC (linear predictive coding) vocoder which increases the clarity and naturalness of the output speech. This synthesizer enhances the usual excitations of either periodic pulses or white noise by allowing pulse\\/noise mixtures and aperiodic pulses, and thus can generate a wider range of possible speech signals. The control algorithms for this

Alan V. McCree; Thomas P. Barnwell

1991-01-01

323

Electron Impact Excitation and Ionization of Neon  

NASA Astrophysics Data System (ADS)

We have further developed the B-Spline R-matrix (BSR) code [1] to allow for a large number of pseudo-states in the close-coupling expansion. In the present work, the BSRMPS approach [2] was employed to perform semi-relativistic (Breit-Pauli) close-coupling calculations for elastic scattering, excitation, and ionization of neon from both the ground state and the metastable excited states. Coupling to the ionization continuum through the pseudo-states is important for low-energy elastic scattering (to represent polarizability effects), for excitation in the ``intermediate'' energy regime of about 1-5 times the ionization potential, and to allow for the calculation of ionization processes by transforming the results obtained for excitation of the positive-energy pseudo-states. The current results represent a significant extension of our earlier near-threshold work [3] and previous non-relativistic RMPS calculations [4,5].[4pt] [1] O. Zatsarinny, Comp. Phys. Commun. 174 (2006) 273.[0pt] [2] O. Zatsarinny and K. Bartschat, Phys. Rev. Lett. 107 (2011) 023203.[0pt] [3] O. Zatsarinny and K. Bartschat, J. Phys. B 37 (2004) 2173.[0pt] [4] C. P. Ballance and D. C. Griffin, J. Phys. B 37 (2004) 2943.[0pt] [5] C. P. Ballance et al., J. Phys. B 37 (2004) 4779.

Zatsarinny, Oleg; Bartschat, Klaus

2012-10-01

324

ESD excitation model for susceptibility study  

Microsoft Academic Search

The paper provides a simplified model of a known ESD generator that allows modeling the ESD impulses (current and fields) in CST-Microwave Studio. The model is suitable for simulating the excitation of structures by ESD, but it is not intended to predict the fields and current of an ESD generator for its development purpose. The aim is to simultaneously model

Federico Centola; David Pommerenke; Wang Kai; T. Van Doren; S. Caniggia

2003-01-01

325

Precision Dentistry Offers Exciting New Options  

E-print Network

Precision Dentistry Offers Exciting New Options UCSF Launches Center for Children's Oral Health / 2014 University of California, San Francisco magazine School of Dentistry #12;dentistry.ucsf.edu VOLUME 9 / 2014 Update > Featherstone Renewed as Dean for Five Years / PAGE 2 > UCSF Dentistry Joins All

Derisi, Joseph

326

On the excitation of Goodwin's oscillations  

NASA Astrophysics Data System (ADS)

We consider the necessary condition for excitation of long-periodic Goodwin's oscillations and short-periodic sawtooth oscillations in the Goodwin model with fixed delay in the induced investment. Also, using the method of equivalent linearization we evaluate the amplitude of steady-state oscillation.

Antonova, A. O.; Reznik, S. N.; Todorov, M. D.

2014-11-01

327

Elastic continua in high frequency excitation field  

Microsoft Academic Search

The response of elastic continua to high-frequency excitations is decomposed in two parts: 'slow' motion which practically remains unchanged during a vanishingly small period of time, and 'fast' motions whose mean value during this period is negligible but whose energy contribution is essential. After such a decomposition the 'slow' and 'fast' motions become non-linearly coupled by the corresponding governing equations.

M. Zak

1984-01-01

328

Asymptotic properties of mathematical models of excitability  

E-print Network

the stationary rotation of a spiral wave is unstable against alternans (Nolasco & Dahlen 1968; Karma et al. 1994 this analysis to study the behaviour of fronts of excitation waves in spatially extended cardiac models. Such a dissipation may happen if a front propagates into a tissue recovering after a previous wave, e.g. re- entry

Simitev, Radostin D

329

Ionic electrostatic excitations along biological membranes  

NASA Astrophysics Data System (ADS)

A theoretical analysis of ionic electrostatic excitations of a charged biological membrane is presented within the framework of the fluid theory for surface ions inside and outside the cell, in conjunction with the Poisson's equation. General expressions of dispersion relations are obtained for electrostatic oscillations of intrinsic cellular with different shapes and symmetries.

Moradi, Afshin

2011-02-01

330

Collisional excitation of intersteller molecules: Ammonia  

NASA Technical Reports Server (NTRS)

Theoretical rate constants are presented for excitation of NH3 by collisions with He. The lowest 22 levels of ortho-NH3 and the lowest 16 levels of para-NH3 are considered at kinetic temperatures of 15 to 300 K.

Green, S.

1981-01-01

331

Excitation system for rotating synchronous machines  

DOEpatents

A system for providing DC current to a rotating superconducting winding is provided. The system receives current feedback from the superconducting winding and determines an error signal based on the current feedback and a reference signal. The system determines a control signal corresponding to the error signal and provides a positive and negative superconducting winding excitation voltage based on the control signal.

Umans, Stephen D. (Belmont, MA); Driscoll, David J. (South Euclid, OH)

2002-01-01

332

Observation of orbitally excited B mesons  

Microsoft Academic Search

Experimental evidence for the existence of orbitally excited B meson states is presented in an analysis of the B? and B?? distribution of Q = m(B??) ? m(B(?)) ? m(?) using Z0 decay data taken with the DELPHI detector at LEP.The mean Q-value of the decays B?? ? B(?)? is measured to be 284 ± 5 (stat.) ± 15 (syst.)

P. P. Abreu; W. Adam; T. Adye; E. Agasi; I. Ajinenko; Roy Aleksan; G. D. Alekseev; P. P. Allport; S. Almehed; F. M. L. Almeida; S. J. Alvsvaag; Ugo Amaldi; S. Amato; A. Andreazza; M. L. Andrieux; P. Antilogus; W.-D. Apel; Y. Arnoud; B. Åsman; J.-E. Augustin; A. Augustinus; Paul Baillon; P. Bambade; F. Barao; R. Barate; Guido Barbiellini; Dimitri Yuri Bardin; G. J. Barker; A. Baroncelli; O. Barring; J. A. Barrio; Walter Bartl; M. J. Bates; Marco Battaglia; M. Baubillier; J. Baudot; K.-H. Becks; M. Begalli; P. Beilliere; Yu A Belokopytov; P. Beltran; Alberto C Benvenuti; M. Berggren; D. Bertrand; F. Bianchi; M. Bigi; M. S. Bilenky; P. Billoir; J. Bjarne; D. Bloch; M. Blume; S. Blyth; V. Bocci; T. Bolognese; M. Bonesini; W. Bonivento; P. S. L. Booth; G. Borisov; C. Bosio; B. Bostjancic; S. Bosworth; O. Botner; B. Bouquet; C. Bourdarios; T. J. V. Bowcock; M. Bozzo; P. Branchini; K. D. Brand; R. A. Brenner; H. Briand; C. Bricman; L. Brillault; R. C. A. Brown; P. Bruckman; J.-M. Brunet; L. Bugge; T. Buran; A. Buys; M. Caccia; M. Calvi; A. J. Camacho Rozas; T. Camporesi; V. Canale; M. Canepa; K. Cankocak; F. Cao; F. Carena; P. Carrilho; L. Carroll; Carlo Caso; V. Cassio; M. V. Castillo Gimenez; A. Cattai; F. R. Cavallo; L. Cerrito; V. Chabaud; A. Chan; Ph. Charpentier; L. Chaussard; J. Chauveau; P. Checchia; G. A. Chelkov; P V Chliapnikov; P. Chochula; V. Chorowicz; J. T. M. Chrin; V. Cindro; P. Collins; J. L. Contreras; R. Contri; E. Cortina; G. Cosme; F. Cossutti; H. B. Crawley; D J Crennell; G. Crosetti; J. Cuevas Maestro; S. Czellar; Erik Dahl-Jensen; J. Dahm; B. Dalmagne; M. Dam; G. Damgaard; A. Daum; P. D. Dauncey; Martyn Davenport; W. Da Silva; C. Defoix; G. Della Ricca; P A Delpierre; N. Demaria; A. De Angelis; H. De Boeck; Wim de Boer; S. De Brabandere; C. De Clercq; M. D. M. De Fez Laso; C. De La Vaissiere; B. De Lotto; A. De Min; L S De Paula; C. De Saint-Jean; H. Dijkstra; Lucia Di Ciaccio; F. Djama; J. Dolbeau; M. Donszelmann; K. Doroba; M. Dracos; J. Drees; K.-A. Drees; M. Dris; Y. Dufour; F. Dupont; D M Edsall; R. Ehret; T J C Ekelöf; Gösta Ekspong; M. Elsing; J.-P. Engel; N. Ershaidat; M. Espirito Santo; D. Fassouliotis; Michael Feindt; A. Fenyuk; A. Ferrer; T. A. Filippas; A. Firestone; H. Foeth; E. Fokitis; F. Fontanelli; F. Formenti; J.-L. Fousset; B J Franek; P. Frenkiel; D E C Fries; A. G. Frodesen; R. Fruhwirth; F. Fulda-Quenzer; H. Furstenau; J A Fuster; D. Gamba; M. Gandelman; C. Garcia; J. Garcia; C. Gaspar; U. Gasparini; Ph. Gavillet; E. N. Gazis; D. Gele; J.-P. Gerber; D. Gillespie; R. Gokieli; B. Golob; J. J. Gomez Y Cadenas; Gian P Gopal; L. Gorn; M. Gorski; Valerio Gracco; F. Grard; E. Graziani; G. Grosdidier; P. Gunnarsson; J. Guy; U. Haedinger; F. Hahn; M. Hahn; S. Hahn; S. Haider; Z. Hajduk; A. Hakansson; A. Hallgren; K. Hamacher; W. Hao; F. J. Harris; V. Hedberg; R P Henriques; J. J. Hernandez; J. A. Hernando; P. Herquet; H. Herr; T. L. Hessing; E. Higon; Hans Jürgen Hilke; T. S. Hill; S.-O. Holmgren; P. J. Holt; D J Holthuizen; P. F. Honore; M A Houlden; Josef Hrubec; K. Huet; K. Hultqvist; P. Ioannou; J. N. Jackson; R. Jacobsson; P. Jalocha; R. Janik; G. Jarlskog; P. Jarry; B. Jean-Marie; E. K. Johansson; L B Jönsson; P. Juillot; M. Kaiser; George Ernest Kalmus; F. Kapusta; M. Karlsson; E. Karvelas; S. Katsanevas; E. C. Katsoufis; R. Keranen; B. A. Khomenko; N N Khovanskii; B J King; N. J. Kjaer; H. Klein; A. Klovning; P M Kluit; J. H. Koehne; B. Koene; P. Kokkinias; M. Koratzinos; V. Kostioukhine; C. Kourkoumelis; O. Kouznetsov; P.-H. Kramer; Manfred Krammer; C. Kreuter; J. Krolikowski; I J Kronkvist; Z Krumshtein; W. Krupinski; P. Kubinec; W. Kucewicz; K. Kulka; K L Kurvinen; C. Lacasta; I. Laktineh; C. Lambropoulos; J. W. Lamsa; L. Lanceri; P. Langefeld; V. Lapin; I. Last; J.-P. Laugier; R. Lauhakangas; Gerhard Leder; F. Ledroit; V. Lefebure; C. K. Legan; R. Leitner; Y. Lemoigne; J. Lemonne; Georg Lenzen; V. Lepeltier; T. Lesiak; R. Lindner; A. Lipniacka; I. Lippi; B. Loerstad; M. Lokajicek; J. G. Loken; A. Lopez-Fernandez; M. A. Lopez Aguera; D. Loukas; J Lozano-Bahilo; P. Lutz; L. Lyons; G. Maehlum; J. Maillard; A. Maio; A. Maltezos; V. Malychev; F. Mandl; J. Marco; B. Marechal; M. Margoni; J.-C. Marin; C. Mariotti; A. Markou; T. Maron; C. Martinez-Rivero; F. Martinez-Vidal; S. Marti i Garcia; F. Matorras; C. Matteuzzi; Giorgio Matthiae; M. Mazzucato; M. Mc Cubbin; R. Mc Kay; R. Mc Nulty; J. Medbo; C. Meroni; W. T. Meyer; M. Michelotto; E. Migliore; I. Mikulec; L. Mirabito; Winfried A Mitaroff; U. Mjoernmark; T. Moa; R. Moeller; K. Moenig; M. R. Monge; P. Morettini; H. Mueller; W. J. Murray; B. Muryn; Gerald Myatt; F. Naraghi; Francesco Luigi Navarria; S. Navas; P. Negri; S. Nemecek; W. Neumann; N. Neumeister; R. Nicolaidou; B. S. Nielsen; V. Nikolaenko; P. Niss; A. Nomerotski

1995-01-01

333

HEASARC - The High Energy Astrophysics Science Archive Research Center  

NASA Technical Reports Server (NTRS)

The High Energy Astrophysics Science Archive Research Center (HEASARC) is NASA's archive for high-energy astrophysics and cosmic microwave background (CMB) data, supporting the broad science goals of NASA's Physics of the Cosmos theme. It provides vital scientific infrastructure to the community by standardizing science data formats and analysis programs, providing open access to NASA resources, and implementing powerful archive interfaces. Over the next five years the HEASARC will ingest observations from up to 12 operating missions, while serving data from these and over 30 archival missions to the community. The HEASARC archive presently contains over 37 TB of data, and will contain over 60 TB by the end of 2014. The HEASARC continues to secure major cost savings for NASA missions, providing a reusable mission-independent framework for reducing, analyzing, and archiving data. This approach was recognized in the NRC Portals to the Universe report (2007) as one of the HEASARC's great strengths. This poster describes the past and current activities of the HEASARC and our anticipated developments in coming years. These include preparations to support upcoming high energy missions (NuSTAR, Astro-H, GEMS) and ground-based and sub-orbital CMB experiments, as well as continued support of missions currently operating (Chandra, Fermi, RXTE, Suzaku, Swift, XMM-Newton and INTEGRAL). In 2012 the HEASARC (which now includes LAMBDA) will support the final nine-year WMAP data release. The HEASARC is also upgrading its archive querying and retrieval software with the new Xamin system in early release - and building on opportunities afforded by the growth of the Virtual Observatory and recent developments in virtual environments and cloud computing.

Smale, Alan P.

2011-01-01

334

iBiology: communicating the process of science.  

PubMed

The Internet hosts an abundance of science video resources aimed at communicating scientific knowledge, including webinars, massive open online courses, and TED talks. Although these videos are efficient at disseminating information for diverse types of users, they often do not demonstrate the process of doing science, the excitement of scientific discovery, or how new scientific knowledge is developed. iBiology (www.ibiology.org), a project that creates open-access science videos about biology research and science-related topics, seeks to fill this need by producing videos by science leaders that make their ideas, stories, and experiences available to anyone with an Internet connection. PMID:25080124

Goodwin, Sarah S

2014-08-01

335

iBiology: communicating the process of science  

PubMed Central

The Internet hosts an abundance of science video resources aimed at communicating scientific knowledge, including webinars, massive open online courses, and TED talks. Although these videos are efficient at disseminating information for diverse types of users, they often do not demonstrate the process of doing science, the excitement of scientific discovery, or how new scientific knowledge is developed. iBiology (www.ibiology.org), a project that creates open-access science videos about biology research and science-related topics, seeks to fill this need by producing videos by science leaders that make their ideas, stories, and experiences available to anyone with an Internet connection. PMID:25080124

Goodwin, Sarah S.

2014-01-01

336

Try Science  

NSDL National Science Digital Library

Try Science is a website supported by IBM Corporation, the New York Hall of Science (NYHOS), the Association of Science-Technology Centers (ASTC), and science centers worldwide. The site provides a variety of mathematics, science and technology experiments and activities for students. Many of the activities are interactive, although the experiments are largely meant to be conducted offline. A section on Field Trips allows visitors to search for local science centers, which are described as "places where people of all ages can learn at their own pace, engage their curiosity, use their senses to ask and answer questions, and explain to others what they have learned." Webcams are set up to let visitors view activities at select science and technology centers worldwide. A section for teachers provides suggestions for how to use TryScience in the Classroom, discusses how the website meets Standards in the U.S, Australia and United Kingdom, offers some testimony from teachers who have used TryScience, and lists several professional development programs offered by science centers. Parents will also find a section with some helpful information about science and education along with resources on ways to get involved. Sending one of the Try Science experiments home with students is one suggested way that teachers can get parents involved in their kid's science education. Note that many of the pages require Flash plug-ins.

337

Exciting Students through VEX Robotic Competitions  

ERIC Educational Resources Information Center

Robotic competitions continue to gain popularity in the educational community as a way to engage students in hands-on learning that can raise a student's interest in science, technology, engineering, and mathematics. In 1992, For Inspiration and Recognition of Science and Technology (FIRST) held its first competition and presented a style of…

Robinson, Trevor P.; Stewardson, Gary A.

2012-01-01

338

Science Sampler: A (minty) fresh approach to science fair projects  

NSDL National Science Digital Library

Many students are excited at the prospect of doing a science fair project, but they don't know how to go about asking an appropriate question or designing an experiment to answer their question. This class activity allows students to quickly "do" a class science fair project in order to see how it's done. It's also a great way to introduce concepts of controlling variables and testing multiple subjects using an inexpensive breath mint. Even if you do not do science fair projects with your class, this is a terrific activity for the beginning of the year as an introduction to the process of scientific inquiry. Students discover how to ask a simple question and collect data to answer it in a step-by-step fashion.

Nancy Balter

2007-02-01

339

Cascadable excitability in optically injected microdisks  

NASA Astrophysics Data System (ADS)

All-optical spiking neural networks would allow high speed parallelized processing of time-encoded information, using the same energy efficient computational principles as our brain. As the neurons in these networks need to be able to process pulse trains, they should be excitable. Using simulations, we demonstrate Class 1 excitability in optically injected microdisk lasers, and propose a cascadable optical spiking neuron design. The neuron has a clear threshold and an integrating behavior. In addition, we show that the optical phase of the input pulses can be used to create inhibitory, as well as excitatory perturbations. Furthermore, we incorporate our optical neuron design in a topology that allows a disk to react on excitations from other disks. Phase tuning of the intermediate connections allows to control the disk response. Additionally, we investigate the sensitivity of the disk circuit to deviations in driving current and locking signal wavelength detuning. Using state-of-the-art fabrication techniques for microdisk laser, the standard deviation of the lasing wavelength is still about one order of magnitude too large. Finally, as the dynamical behavior of the microdisks is identical to the behavior in Semiconductor Ring Lasers (SRL), we compare the excitability mechanism due to optically injection with the previously proposed excitability due to asymmetry in the intermodal coupling in SRLs, as the latter mechanism can also be induced in disks due to, e.g., asymmetry in the external reaction. In both cases, the symmetry between the two counter-propagating modes of the cavity needs to be broken to prevent switching to the other mode, and allow the system to relax to its initial state after a perturbation. However, the asymmetry due to optical injection results in an integrating spiking neuron, whereas the asymmetry in the intermodal coupling is known to result in a resonating spiking neuron.

Van Vaerenbergh, Thomas; Alexander, Koen; Fiers, Martin; Mechet, Pauline; Dambre, Joni; Bienstman, Peter

2014-05-01

340

Forensic Science  

ERIC Educational Resources Information Center

A course is described, which was given during an interim, with an enrollment of 41 students. The course involved an in-depth study of forensic science, involving students with the methodology of science. (DF)

Berry, Keith O.; Nigh, W. G.

1973-01-01

341

Science Alive!  

NSDL National Science Digital Library

An elementary school brings in community volunteers for a full-day, all-school event focused on real world science. This article describes the planning process and types of science professionals and non-professionals recruited for the event.

Kay Tally-Foos

2005-01-01

342

Science | Poster  

Cancer.gov

Skip to main content About Us Services Science For Our Staff Phonebook Poster Search form Search Main menu Home Science Publications Platinum Highlight Platinum Publications Technology Transfer Awards Health and Safety Outreach Students Features Poster

343

Science Notes.  

ERIC Educational Resources Information Center

Presented are 29 science activities for secondary school science instruction. Topic areas include botany, genetics, biochemistry, anatomy, entomology, molecular structure, spreadsheets, chemistry, mechanics, astronomy, relativity, aeronautics, instrumentation, electrostatics, quantum mechanics, and laboratory interfacing. (CW)

School Science Review, 1990

1990-01-01

344

Science Fiction and Science Literacy  

NSDL National Science Digital Library

Science fiction is read not only for enjoyment, but because it digs into scientific concepts with imagination, creativity, and a thorough appreciation of consequence. It has so much to offer in terms of good science and how science works, while at the same time addressing the basics of literacy. In this article, the author makes a case for why science fiction should be a part of science curricula and provides an all-purpose, critical reading activity to help teachers use science fiction in the classroom.

Julie E. Czerneda

2006-02-01

345

Understanding Science  

NSDL National Science Digital Library

This page, from University of California Museum of Paleontology, features free, image-rich teaching resources that communicate what science is and how it works, with a focus on the process of science and its dynamic nature. The project is geared toward K-16 teacher preparation as well as broader public understanding of the nature of science.

University of California Museum of Paleontology

346

Safer Science  

ERIC Educational Resources Information Center

This column provides best safety practices for the science classroom and laboratory. In this month's issue, pregnancy policy in the laboratory is discussed. One can't ignore the fact that student and faculty pregnancies--and the resulting potential hazards in the science laboratory--exist at the high school level. Science teachers need to be…

Roy, Ken

2011-01-01

347

Science Facilities  

ERIC Educational Resources Information Center

The National Research Council's "National Science Education Standards" call for science education to be "developmentally appropriate, interesting, and relevant to students' lives, emphasize student understanding through inquiry, and be connected with other school subjects." This description captures the three major trends in science education…

Butin, Dan W.; Biehle, James T.; Motz, LaMoine L.; West, Sandra S.

2009-01-01

348

Dramatic Science  

ERIC Educational Resources Information Center

The setting: the science classroom. The characters: you and your students. The scene: Your students acting out scientific discoveries, modeling a frog's life cycle, mimicking the transition from liquid to solid. This is "dramatic science", a teaching approach that uses acting techniques to explore and develop young children's ideas about science

McGregor, Debbie; Precious, Wendy

2010-01-01

349

Sublime Science  

ERIC Educational Resources Information Center

One of the shortcomings in most efforts to integrate art and science is that many people have a shallow understanding of art, which inevitably leads to shallow connections between art and science. Coloring drawings of planets, building sculptures of volcanoes, and decorating scientific diagrams are fine activities, but they do not link science and…

Girod, Mark

2007-01-01

350

Watershed Science.  

ERIC Educational Resources Information Center

Presents activities from an interdisciplinary project studying local watersheds that incorporate a broad spectrum of disciplines including science, math, geography, English, computer science, and political science. Enables students to understand how precipitation changes chemically as it interacts with the soils and human-altered landscape as it…

Green, Tom

1996-01-01

351

Science Nation: Citizen Science  

NSDL National Science Digital Library

Citizen science has been around for centuries, with lay people collecting data and making observations for scientists in a variety of fields. And, citizen scientists are contributing to discoveries as much in the 21st century as ever before. The Internet has made a huge impact on the volume of information scientists can obtain from lay people, especially in the fields of ornithology and astronomy. One program is NestWatch was developed by Cornell University, in collaboration with the Smithsonian Migratory Bird Center, and is funded by NSF.

352

Enhanced production of excited neutrals following core-to-Rydberg excitation in molecules: SiCl4  

NASA Astrophysics Data System (ADS)

Using monochromatized synchrotron radiation in the range 103 to 112 eV we have monitored the dispersed UV/optical fluorescence resulting from excitation of a Si 2p electron in SiCl4. The main features in the fluorescence spectrum have been identified as emission from the SiCl4+ C state and from excited Si atoms. Features in the fluorescence excitation spectra are assigned to excitation of a Si 2p electron to unoccupied valence and Rydberg orbitals. For the SiCl4+ C state emission there is significant enhancement in the yield following excitation to valence orbitals and very little enhancement as a result of Rydberg excitation. The opposite is true for emission from excited Si atoms. Enhancement in the SiCl4+ C state production upon valence excitation results from autoionization of the core-excited state. The relatively large yield of excited Si atoms following Rydberg excitation is due to the greater probability of the core-excited Rydberg state decaying, via a resonant Auger process, to highly excited, unbound states of SiCl4+. The molecular ion then fragments before the excited Rydberg electron can relax.

Rosenberg, R. A.; Wen, C.-R.; Tan, K.; Chen, J.-M.

1990-04-01

353

ComputationalComputational ScienceScience  

E-print Network

ComputationalComputational ScienceScience KenKen HawickHawick k.a.k.a.hawickhawick@massey.ac.nz@massey.ac.nz Massey UniversityMassey University #12;Computational Science / eScienceComputational Science / eScience Computational Science concerns the application of computer science to physics, mathematics, chemistry, biology

Hawick, Ken

354

High resolution fluorescent bio-imaging with electron beam excitation.  

PubMed

We have developed electron beam excitation assisted (EXA) optical microscope[1-3], and demonstrated its resolution higher than 50 nm. In the microscope, a light source in a few nanometers size is excited by focused electron beam in a luminescent film. The microscope makes it possible to observe dynamic behavior of living biological specimens in various surroundings, such as air or liquids. Scan speed of the nanometric light source is faster than that in conventional near-field scanning optical microscopes. The microscope enables to observe optical constants such as absorption, refractive index, polarization, and their dynamic behavior on a nanometric scale. The microscope opens new microscopy applications in nano-technology and nano-science.Figure 1(a) shows schematic diagram of the proposed EXA microscope. An electron beam is focused on a luminescent film. A specimen is put on the luminescent film directly. The inset in Fig. 1(a) shows magnified image of the luminescent film and the specimen. Nanometric light source is excited in the luminescent film by the focused electron beam. The nanometric light source illuminates the specimen, and the scattered or transmitted radiation is detected with a photomultiplier tube (PMT). The light source is scanned by scanning of the focused electron beam in order to construct on image. Figure 1(b) shows a luminescence image of the cells acquired with the EXA microscope, and Fig. 1(c) shows a phase contrast microscope image. Cells were observed in culture solution without any treatments, such as fixation and drying. The shape of each cell was clearly recognized and some bright spots were observed in cells. We believe that the bright spots indicated with arrows were auto-fluorescence of intracellular granules and light- grey regions were auto-fluorescence of cell membranes. It is clearly demonstrated that the EXA microscope is useful tool for observation of living biological cells in physiological conditions.jmicro;63/suppl_1/i16/DFU090F1F1DFU090F1Fig. 1.(a) Optical setup of EXA microscpe, and observation results of of living MARCO-expressing CHO cells with (b) EXA microscope and (c) phase contrast microscope. We proposed the EXA microscope as a technique with high spatial resolution beyond the diffraction limit of light. A spatial resolution greater than 100 nm was achieved for the EXA microscope and the dynamic behavior of moving nanoparticles in water was observed by time lapse imaging. We also demonstrated luminescence image of living cells in culture solution without any treatments. PMID:25359807

Kawata, Yoshimasa; Nawa, Yasunori; Inami, Wataru

2014-11-01

355

Delivering SKA Science  

E-print Network

The SKA will be capable of producing a stream of science data products that are Exa-scale in terms of their storage and processing requirements. This Google-scale enterprise is attracting considerable international interest and excitement from within the industrial and academic communities. In this chapter we examine the data flow, storage and processing requirements of a number of key SKA survey science projects to be executed on the baseline SKA1 configuration. Based on a set of conservative assumptions about trends for HPC and storage costs, and the data flow process within the SKA Observatory, it is apparent that survey projects of the scale proposed will potentially drive construction and operations costs beyond the current anticipated SKA1 budget. This implies a sharing of the resources and costs to deliver SKA science between the community and what is contained within the SKA Observatory. A similar situation was apparent to the designers of the LHC more than 10 years ago. We propose that it is time for...

Quinn, Peter; Bird, Ian; Dodson, Richard; Szalay, Alex; Wicenec, Andreas

2015-01-01

356

Science Buddies  

NSDL National Science Digital Library

The Science Buddies program pairs a seventh-grade life science class with a second-or third-grade class in a yearlong partnership of science adventures. Over the course of the year these dual-grade learning groups work together on various science explorations--gardening, weather observation, and others--to explore concepts and practice science-process skills such as predicting, gathering, and analyzing data. The program has run for two years at our school and has been truly successful with both students and teachers.

Susan Ade Potenza

2003-01-01

357

1 Organizational Sciences and Communication ORGANIZATIONAL SCIENCES  

E-print Network

1 Organizational Sciences and Communication ORGANIZATIONAL SCIENCES AND COMMUNICATION The communication and organizational sciences majors are offered by the Department of Organizational Sciences. The Department of Organizational Sciences and Communication offers interdisciplinary programs leading

Vertes, Akos

358

Interaction of highly vibrationally excited molecules with clean metal surfaces. Final technical report  

SciTech Connect

The authors present results from a grant funded under the Department of Energy Office of Basic Energy Sciences. A collaboration between Prof. Alec Wodtke of the Department of Chemistry at UCSB and Daniel J. Auerbach of IBM Almaden Research Labs has allowed new experiments on the dynamics of surface chemical reactivity to be successfully executed. High quality data has been generated which provides an excellent test of theoretical models of surface reactivity, a topic of importance to catalysis. The authors have obtained the first experimental measurements on the influence of reactant velocity on the steric effect in a chemical reaction: the dissociative adsorption of hydrogen on copper. They have also designed and built a molecular beam scattering apparatus for the study of highly vibrationally excited molecules and their interactions with clean and oxidized metal surfaces. With this apparatus they have observed the vibrational energy exchange of highly vibrationally excited NO with an oxidized copper surface. Multi-quantum vibrational relaxation was found ({Delta}v = 1-5). Such remarkably strong and efficient vibrational energy transfer represents a qualitatively new phenomenon and is representative of the exciting new behavior that they had hoped might be observable in this project. Evidence of chemical reactivity of vibrationally excited NO on a clean copper surface was also found.

Wodtke, A.M. [Univ. of California, Santa Barbara, CA (United States). Dept. of Chemistry; Auerbach, D.J. [IBM Almaden Research Center, San Jose, CA (United States)

1998-11-01

359

Impulse excitation of piezoelectric bimorphs for energy harvesting: a dimensionless model  

NASA Astrophysics Data System (ADS)

Energy harvesting (EH) is a multidisciplinary research area, involving physics, materials science and engineering, with the objective of providing renewable sources of power sufficient to operate targeted low-power applications. Piezoelectric transducers are often used for inertial vibrational as well as direct excitation EH. However, due to the stiffness of the most common material (PZT), compact and light-weight harvesters have high resonant frequencies, making them inefficient at extracting low-frequency power from the environment. The technique of frequency up-conversion, in the form of either plucking or impulse excitation, aims to bridge this frequency gap. In this paper, the technique is modelled analytically with focus on impulse excitation via impact or shock. An analytical model is developed in a standard way starting from the Euler-Bernoulli beam equations adapted to a piezoelectric bimorph. A set of dimensionless variables and parameters is defined and a system of differential equations derived. Here the system is solved numerically for a wide range of the two group parameters present, covering piezoelectric coupling strength between PVDF and PMN-PT. One major result is that the strength of the coupling strongly affects the timescale of the process, but has only a minor effect on the total energy converted. The model can be readily adapted to different excitation profiles.

Pozzi, Michele

2014-04-01

360

Science Squared: Teaching Science Visually.  

ERIC Educational Resources Information Center

This paper describes a collection of novel ideas for bulletin board displays that would be useful in supplementing science classroom instruction. Information on women and minorities in science; science concepts in everyday activities such as nutrition, baseball, and ice cream-making; and various holidays and celebratory events is included. Each…

Paradis, Olga; Savage, Karen; Judice, Michelle

361

1 Biological Sciences BIOLOGICAL SCIENCES  

E-print Network

biology of plants and animals. Laboratory fee. (Fall). BISC 1112. Introductory Biology: The Biology biology; diversity of plants, animals, fungi, and microorganisms; ecology and behavior; and animal1 Biological Sciences BIOLOGICAL SCIENCES As one of the natural science departments in GW

Vertes, Akos

362

Excitation of millimeter and submillimeter water masers  

NASA Technical Reports Server (NTRS)

The excitation of maser emission in millimeter and submillimeter transitions of interstellar and circumstellar water is considered. An escape probability method is used to determine the equilibrium populations in 349 rotational states of both ortho- and para-water under varying conditions of gas temperature, density, water abundance, and radiation field. It is shown that, under those conditions believed to prevail around late-type stars and within star-forming regions, strong millimeter and submillimeter water maser emission can be generated by collisional excitations by H2. Several maser transitions can have strengths close to that of the 22 GHz line. The water maser line which can be observed from mountaintop facilities and those which will require air- or space-borne platforms are indicated. The exact portion of parameter space in which each maser transition exhibits peak emission is shown.

Neufeld, David A.; Melnick, Gary J.

1991-01-01

363

Viscous flow drag reduction by acoustic excitation  

NASA Technical Reports Server (NTRS)

An experimental program in which the effectiveness of a single large eddy break up (LEBU) blade is enhanced by proper acoustic excitation is described. Acoustic waves are generated in response to the incident large scale eddies and directed at the blade trailing edge through the test surface floor below the manipulator blade. The acoustic input is phase locked to the incident flow. Control of the acoustic input apparently allows enhancement of the large eddy cancellation process leading to a decrease of skin friction coefficient. Control of this process with acoustic excitation indicates that vortex unwinding is the mechanism for large eddy destruction in the boundary layer. A deeper understanding of this phenomena could lead to better drag reduction technology and further understanding of the physics of the turbulent boundary layer.

Nagel, Robert T.

1986-01-01

364

[Anesthesia mechanisms: nerve excitation and temperature].  

PubMed

Depolarization of a nerve membrane produces heat while repolarization absorbs heat. This is equivalent to the phase transition of water where freezing of water produces heat and melting of ice absorbs heat. In this context, high temperature (as in water) supports resting potential and low temperature (as in ice) supports action potential. When assessed by the equilibrium between the two phases, anesthetized state is the high temperature state. Nevertheless, low temperature supports anesthesia. The two opposing facts confuse the understanding of anesthesia mechanisms. The inconsistency arises from the two effects of heat on nerve excitation. One is one the equilibrium between the resting and active states of the excitation machinery, and the other is on the reaction rate process. This review annot?atsz why low temperature facilitates anesthesia while high temperature supports the resting state of nerves. PMID:8752767

Suzuki, A; Ueda, I

1996-06-01

365

Universality of plasmon excitations in Dirac semimetals  

E-print Network

The recent experimental discovery of ${\\rm Cd_3 As_2}$ and ${\\rm Na_3 Bi}$ Dirac semimetals enables the study of the properties of chiral quasi-particles in three spatial dimensions. As demonstrated by photoemission, Dirac semimetals are characterized by a linear dispersion relation for fermion quasi-particles, and thus represent three dimensional analogs of graphene. While the distinctive behavior of chiral fermions (e.g. Klein tunneling) is already evident in two dimensional graphene, the physics of chirality in three dimensions opens a number of new possibilities. In this paper we investigate the properties of the collective plasmon excitations in Dirac semimetals by using the methods of relativistic field theory. We find a strong and narrow plasmon excitation whose frequency is in the terahertz (THz) range which may be important for practical applications. The properties of the plasmon appear universal for all Dirac semimetals, due to the large degeneracy of the quasi-particles and the small Fermi velocit...

Kharzeev, Dmitri E; Yee, Ho-Ung

2014-01-01

366

Electron-impact excitation of neutral oxygen  

E-print Network

Aims: To calculate transition rates from ground and excited states in neutral oxygen atoms due to electron collisions for non-LTE modelling of oxygen in late-type stellar atmospheres, thus enabling reliable interpretation of oxygen lines in stellar spectra. Methods: A 38-state R-matrix calculation in LS-coupling has been performed. Basis orbitals from the literature (Thomas et al.) are adopted, and a large set of configurations are included to obtain good representations of the target wavefunctions. Rate coefficients are calculated by averaging over a Maxwellian velocity distribution. Results: Estimates for the cross sections and rate coefficients are presented for transitions between the seven lowest LS states of neutral oxygen. The cross sections for excitation from the ground state compare well with existing experimental and recent theoretical results.

P. S. Barklem

2006-09-25

367

Multiple excitation modes in 163Hf  

NASA Astrophysics Data System (ADS)

Excited states of 163Hf were populated using the 94Zr(74Ge,5 n ) reaction and the decay ? rays were measured with the Gammasphere spectrometer. Two previously known bands were extended to higher spins, and nine new bands were identified. In addition to bands associated with three- and five-quasiparticle configurations, two ? - vibrational bands coupled to the i13 /2 excitation were also observed. The lowest level of a newly identified, negative-parity band is proposed to be the ground state of the nucleus. A systematic delay of the high-spin proton crossing frequency with increasing quadrupole deformation from 162Hf to 172Hf was established. Extensive band searches failed to reveal a triaxial, strongly deformed structure in 163Hf similar to the one observed in several nuclei around A ˜165 .

Yadav, R. B.; Ma, W. C.; Marsh, J. C.; Ijaz, Q. A.; Janssens, R. V. F.; Carpenter, M. P.; Hoffman, C. R.; Lauritsen, T.; Zhu, S.; Kondev, F. G.; Gürdal, G.; Hagemann, G. B.; Hartley, D. J.; Riedinger, L. L.; Mukhopadhyay, S.

2014-11-01

368

Quasiparticle excitations in Bose-Fermi mixtures  

NASA Astrophysics Data System (ADS)

We analyze the excitation spectrum of a three-dimensional Bose-Fermi mixture with tunable resonant interaction parameters and high hyperfine spin multiplets. We focus on a three-particle vertex describing fermionic and bosonic atoms which can scatter to create fermionic molecules or disassociate. For a single molecular level, in analogy to the single magnetic impurity problem we argue that the low-lying excitations of the mean-field theory are described by the Fermi-liquid picture with a quasiparticle weight and charge which is justified by a 1/N? expansion, expected to be exact in the limit of infinite degeneracy (or very high fermionic spin) N??? . Our emphasis is placed on the novel conditions for chemical equilibrium and how many-body chemical reactions renormalize the bosonic chemical potential, modifying condensation and superfluid-insulator transitions.

Akhanjee, Shimul

2010-08-01

369

Rotational excitations in two-color photoassociation  

SciTech Connect

We show that it is possible to excite higher rotational states J>2 in ultracold photoassociation by two laser fields. Usually higher J states are suppressed in photoassociation at ultracold temperatures in the regime of Wigner threshold laws. We propose a scheme in which one strong laser field drives photoassociation transition close to either J=1 or J=2 rotational state of a particular vibrational level of an electronically excited molecule. The other laser field is tuned near photoassociation resonance with J>2 rotational levels of the same vibrational state. The strong laser field induces a strong continuum-bound dipole coupling. The resulting dipole force between two colliding atoms modifies the continuum states forming continuum-bound dressed states with a significant component of higher partial waves in the continuum configuration. When the second laser is scanned near the resonance of the higher J states, these states become populated due to photoassociative transitions from the modified continuum.

Hazra, Jisha; Deb, Bimalendu [Department of Materials Science and Raman Center for Atomic, Molecular and Optical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

2010-02-15

370

Temperature-dependent Coulomb excitations in silicene  

NASA Astrophysics Data System (ADS)

The temperature-dependent Coulomb screening and excitation spectrum of electrons in silicene are studied by the tight-binding model and the random-phase approximation. With the spin–orbit interaction, monolayer silicene is a narrow-gap semiconductor. At finite temperatures, the interplay between the intraband and interband transitions could lead to an undamped plasmon mode at low frequencies. The plasmon mode only exists in a limited region of temperature and momentum, corresponding to the constrained gap transition. Beyond that region, another damped plasmon mode dominates the excitation spectrum. The drastic change in the plasmon behavior might be observed experimentally, which could allow for the identification of the spin–orbit energy gap.

Wu, J. Y.; Chen, S. C.; Lin, M. F.

2014-12-01

371

The self-excited axisymmetric jet  

NASA Technical Reports Server (NTRS)

The results of a number of investigations suggest that large-scale coherent structures and their interactions play key roles in the transport of heat, mass, and momentum, and in the generation of aerodynamic noise. Investigations related to the study of a large-scale coherent structure in the circular jet are considered, taking into account the advantages of inducing controlled perturbation through self-sustained excitation with the whistler nozzle. The primary objective of the present study was to document the jet response to self-excitation and the sensitivity of this response to the initial condition and the Reynolds number R(D). It was also felt that the results would find use in the control of mixing and aerodynamic noise in a jet.

Hasan, M. A. Z.; Hussain, A. K. M. F.

1982-01-01

372

String excitation inside generic black holes  

E-print Network

We calculate how much a first-quantized string is excited after crossing the inner horizon of charged Vaidya solutions, as a simple model of generic black holes. To quantize a string suitably, we first show that the metric is approximated by a {\\it plane-wave} metric near the inner horizon when the surface gravity of the horizon $\\kappa_I$ is small enough. Next, it is analytically shown that the string crossing the inner horizon is excited infinitely in an asymptotically flat spacetime, while it is finite in an asymptotically de Sitter spacetime and the string can pass across the inner horizon when $\\kappa_I<2\\kappa:= 2 {min}\\{\\kappa_B,\\kappa_C \\}$, where event horizon. This implies that the strong cosmic censorship holds in an asymptotically flat spacetime, while it is violated in an asymptotically de Sitter spacetime from the point of view of string theory.

Maeda, K I; Narita, M; Maeda, Kengo; Torii, Takashi; Narita, Makoto

2000-01-01

373

Wave Optics in Discrete Excitable Media  

NASA Astrophysics Data System (ADS)

Refraction and reflection of planar waves in a discrete excitable medium is numerically investigated by using the Greenberg—Hasting model. It is found that the medium is anisotropic because the speed of the planar wave depends on the excitability of the medium and the direction of wave propagation. The reflection, diffraction, refraction, double refraction and delayed refraction are observed by using the correct choice of model parameters. When the incident angle is larger than the critical angle, the reflection, which is a back refraction, takes place. The reflection angle changes with the incident angle. The refraction in certain situations obeys Snell's law. Also, our results demonstrate that the incident, refracted and reflected waves can have different periods. The reflected and refracted waves can disappear.

Gu, Guo-Feng; Wei, Hai-Ming; Tang, Guo-Ning

2012-05-01

374

Categorization of neural excitability using threshold models.  

PubMed

A classification of spiking neurons according to the transition from quiescence to periodic firing of action potentials is commonly used. Nonbursting neurons are classified into two types, type I and type II excitability. We use simple phenomenological spiking neuron models to derive a criterion for the determination of the neural excitability based on the afterpotential following a spike. The crucial characteristic is the existence for type II model of a positive overshoot, that is, a delayed after depolarization, during the recovery process of the membrane potential. Our prediction is numerically tested using well-known type I and type II models including the Connor, Walter, & McKown (1977) model and the Hodgkin-Huxley (1952) model. PMID:15931706

Tonnelier, A

2005-07-01

375

Earth Rotational Variations Excited by Geophysical Fluids  

NASA Technical Reports Server (NTRS)

Modern space geodetic measurement of Earth rotation variations, particularly by means of the VLBI technique, has over the years allowed studies of Earth rotation dynamics to advance in ever-increasing precision, accuracy, and temporal resolution. A review will be presented on our understanding of the geophysical and climatic causes, or "excitations". for length-of-day change, polar motion, and nutations. These excitations sources come from mass transports that constantly take place in the Earth system comprised of the atmosphere, hydrosphere, cryosphere, lithosphere, mantle, and the cores. In this sense, together with other space geodetic measurements of time-variable gravity and geocenter motion, Earth rotation variations become a remote-sensing tool for the integral of all mass transports, providing valuable information about the latter on a wide range of spatial and temporal scales. Future prospects with respect to geophysical studies with even higher accuracy and resolution will be discussed.

Chao, Benjamin F.

2004-01-01

376

Modeling Excitable Systems Coupled Through External Medium  

NASA Astrophysics Data System (ADS)

Excitable systems are stable dynamical systems in which any input beyond a threshold results in a significant output. This behavior is ubiquitous in nature and is seen in biological systems such as Dictyostelium discoideum amoeba and neurons to oscillatory chemical reactions. In this work we will focus on transition to oscillation in populations of excitable systems coupled through an external medium and will study their synchronization. We will describe a mechanism to tune the frequency of oscillations using an external input and will study the effects of stochasticity and inhomogeneity on the collective behavior of the system. Furthermore we will include diffusion into the dynamics of the external medium and will study formation of spatial patterns, their characteristics and their robustness to different factors.

Noorbakhsh, Javad; Mehta, Pankaj

2013-03-01

377

Multiphonon excitations in boson quantum films  

SciTech Connect

Dynamical excitations in thin liquid films of {sup 4}He adsorbed to a substrate are investigated by using a microscopic theory of excitations that includes multiple-phonon scattering. We study the dispersion relation, excitation mechanisms, transition densities, and particle currents as a function of surface coverage. A primary new result is that we have included three-phonon scattering processes in the calculation of the dynamic structure function and the one-body current densities. With the exception that our ground state is determined by our variational theory, rather than taken from experiment, our work on the dynamic structure function is the generalization of that of Jackson [Phys. Rev. A {bold 4}, 2386 (1971)] to inhomogeneous systems (films). Using sum rules for the dynamic structure function as a guide, we suggest a simple scaling argument for improving the agreement between our dynamic structure function and the experimental one. The addition of three-phonon contributions bring about the following changes. First, the energy of most modes is lowered by a non-negligible amount for finite momentum excitations. Second, the film{close_quote}s surface mode is the exception; it is only slightly affected. Third, for monolayer films there is large scattering at high energies at intermediate values of momenta. This scattering can be traced back to an anomalously large contribution to the two-particle density of states. Fourth, all modes with energy above a critical energy decay, and the associated peaks of the dynamic structure function are broadened. Fifth, the maxonlike character is enhanced in the bulklike modes. {copyright} {ital 1996 The American Physical Society.}

Clements, B.E. [Institute Laue Langevin, 38042 Grenoble Cedex (France)] [Institute Laue Langevin, 38042 Grenoble Cedex (France); [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); Krotscheck, E. [Institut fuer Theoretische Physik, Johannes Kepler Universitaet, A-4040 Linz (Austria)] [Institut fuer Theoretische Physik, Johannes Kepler Universitaet, A-4040 Linz (Austria); [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); Tymczak, C.J. [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)] [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)

1996-05-01

378

Nonlinear electromagnetic excitation of ultrasound in metals  

NASA Astrophysics Data System (ADS)

The nonlinear electromagnetic generation of longitudinal ultrasound under anomalous skin effect conditions is investigated theoretically. It is shown that, in the weak nonlinear regime, deformation force serves as the main source of excitation of double-frequency acoustic oscillations. This generation mechanism is related, on the one hand, to the strong spatial inhomogeneity of the electron distribution function, and, on the other, to the presence of a Lorentz force which is due to the magnetic field of the wave.

Vasilev, A. N.; Gulianskii, M. A.; Kaganov, M. I.

1986-07-01

379

Velocity distributions of sputtered excited potassium atoms  

Microsoft Academic Search

We measured the Doppler broadened line profiles of the K I doublet (766.49 and 769.90 nm) emitted by excited K atoms sputtered from KCl and KI single crystal surfaces undergoing energetic Ar+ and Kr+ ion bombardment. The Doppler profiles were analyzed within the framework of the Thompson-Sigmund collision cascade theory. Our results show that (i) the velocity distributions are broader

V. Bissessur; I. S. T. Tsong

1990-01-01

380

Molecular Excitation at high z Franoise Combes  

E-print Network

Molecular Excitation at high z Françoise Combes Paris Observatory, LERMA Z-machines, January 2006 Black-body Tdust 4 - Tbg 4 = cste or optically thin dust ~ 2 Tdust 6 - Tbg 6 = cste #12;13 Model ·Hierarchical theory of galaxy formation Ho = 70km/s/Mpc, with =0.3 =0.7 ·Number of mergers (z) from Press

Groppi, Christopher

381

When inhibition not excitation synchronizes neural firing  

Microsoft Academic Search

Excitatory and inhibitory synaptic coupling can have counter-intuitive effects on the synchronization of neuronal firing. While it might appear that excitatory coupling would lead to synchronization, we show that frequently inhibition rather than excitation synchronizes firing. We study two identical neurons described by integrate-and-fire models, general phase-coupled models or the Hodgkin-Huxley model with mutual, non-instantaneous excitatory or inhibitory synapses between

CARL VAN VREESWIJK; L. F. Abbott; G. Bard Ermentrout

1994-01-01

382

Excitations in Hot Non-Commutative Theories  

E-print Network

We study the dispersion relation for scalar excitations in supersymmetric, non-commutative theories at finite temperature. In N=4 Yang-Mills the low momenta modes have superluminous group velocity. In the massless Wess-Zumino model the minimum of the dispersion relation is at non zero momentum for temperatures above T_0 ~ (g \\theta)^(-1\\2). We briefly comment on N=2 Yang-Mills at finite density.

Landsteiner, K; Tytgat, M H G; Landsteiner, Karl; Lopez, Esperanza; Tytgat, Michel H.G.

2000-01-01

383

Excitations in Hot Non-Commutative Theories  

E-print Network

We study the dispersion relation for scalar excitations in supersymmetric, non-commutative theories at finite temperature. In N=4 Yang-Mills the low momenta modes have superluminous group velocity. In the massless Wess-Zumino model the minimum of the dispersion relation is at non zero momentum for temperatures above T_0 ~ (g \\theta)^(-1\\2). We briefly comment on N=2 Yang-Mills at finite density.

Karl Landsteiner; Esperanza Lopez; Michel H. G. Tytgat

2000-06-27

384

Excitations in hot non-commutative theories  

Microsoft Academic Search

We study the dispersion relation for scalar excitations in supersymmetric, non-commutative theories at finite temperature. In Script N = 4 Yang-Mills the low momentum modes have superluminous group velocity. In the massless Wess-Zumino model the minimum of the dispersion relation is at non zero momentum for temperatures above T0 approx (gtheta)-1\\/2. We briefly comment on Script N = 2 Yang-Mills

Karl Landsteiner; Esperanza Lopez; Michel H. G. Tytgat

2000-01-01

385

Incessant excitation of the Earth's free oscillations  

Microsoft Academic Search

We, for the first time, report the evidence of incessant excitation of the Earth's free oscillations, mainly the fundamental spheroidal modes in a frequency range from 0.3 to 5 mHz, based on the three year record of a superconducting gravimeter at Syowa Station, East Antarctica. The frequency-time spectrogram of this record is striped by more than 30 lines at nGal

K. Nawa; N. Suda; Yoshio Fukao; Tadahiro Sato; Yuichi Aoyama; Kazuo Shibuya

1998-01-01

386

Detecting Breather Excitations with Inelastic Tunneling Spectroscopy  

E-print Network

We propose inelastic electron tunneling spectroscopy scanning tunneling microscopy (IETS-STM) as a means of exciting and observing intrinsic localized modes (breathers) in a macromolecule. As a demonstration, inelastic tunneling features of the density of states are calculated for a simple nonlinear elastic Morse chain. The general formalism we have developed for the IETS is applicable to other nonlinear extended objects, such as DNA on a substrate.

Jian-Xin Zhu; K. O. Rasmussen; A. R. Bishop; A. V. Balatsky

2004-07-08

387

Mobile phone emissions and human brain excitability  

Microsoft Academic Search

Objective: To test—via Transcranial Magnetic Stimulation (TMS)—the excitability of each brain hemisphere after 'real' or 'sham' exposure to the electromagnetic field (EMF) generated by a mobile phone operating in the Global System for Mobile Communication (GSM). Methods: Fifteen male volunteers attended two experimental sessions, one week apart, in a cross-over, double-blind paradigm. In one session the signal was turned ON

Florinda Ferreri; Giuseppe Curcio; Patrizio Pasqualetti; Luigi De Gennaro; Rita Fini; Paolo Maria Rossini

2006-01-01

388

Sheet Excitability and Nonlinear Wave Propagation  

NASA Astrophysics Data System (ADS)

In the Xenopus laevis oocyte, calcium ion channels are clustered in a thin shell. Motivated by this morphology, we study a general class of reaction-diffusion systems that include most of the well-known models that support wave propagation but restricting excitability to a “sheet” of codimension 1. We find waves that undergo propagation failure with increasing diffusion coefficient and a scaling regime in which the wave speed is independent of it.

Pando, Bernardo; Pearson, John E.; Dawson, Silvina Ponce

2003-12-01

389

Spiral core in singly diffusive excitable media  

SciTech Connect

We formulate the problem of finding the spiral core which smoothly matches onto the asymptotic rotating solution of the FitzHugh-Nagumo model. We prove that the inner problem (with scale {epsilon}, the ratio of the reaction rates) has a solution for all possible outer solutions on scale {epsilon}{sup 2/3}; furthermore, we explicitly determine this solution via a simple numerical procedure. This completes the rigorous demonstration of the existence of rotating spiral solutions in singly diffusive excitable systems.

Kessler, D.A. (Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)); Levine, H.; Reynolds, W.N. (Department of Physics and Institute for Nonlinear Science, University of California, San Diego, La Jolla, California 92093 (United States))

1992-01-20

390

Experimental Overview of the Excited Baryon Program  

SciTech Connect

High-energy electrons and photons are a remarkably clean probe of hadronic matter, essentially providing a microscope for examining atomic nuclei and the strong nuclear force. For more than a decade, laboratories worldwide have accumulated data for such investigations, resulting in a number of surprising discoveries and contributing to our understanding of the nucleon, its underlying quark structure, and the dynamics of the strong interaction. One notable discovery has been the unexpected Q{sup 2} variation of the ratio of the proton elastic form-factors G{sub E}{sup p}/G{sub M}{sup p}, which suggests an important contribution from quark orbital angular momentum to the spin of the nucleon. Moreover, the spectrum of excited hadrons can serve as an excellent probe of Quantum Chromodynamics (QCD), the fundamental theory of strong interactions. Since nucleons are complex systems of confined quarks, they exhibit the characteristic spectra of excited states. Highly excited nucleon states are sensitive to details of quark confinement which is poorly understood within QCD. The current effort at facilities worldwide studying the systematics of hadron spectra is to utilize highly-polarized frozen-spin (butanol) and deuterium targets in combination with polarized photon beams. These are important steps toward complete experiments that allow us to unambiguously determine the scattering amplitude in the underlying reactions and to identify resonance contributions.

Crede, Volker [Florida State University, Department of Physics, Tallahassee, FL 32306 (United States)

2011-05-23

391

Excitation energy transfer in the photosystem I  

SciTech Connect

Photosystem I is a multimeric pigment protein complex in plants, green alage and cyanobacteria that functions in series with Photosystem II to use light energy to oxidize water and reduce carbon dioxide. The Photosystem I core complex contains 96 chlorophyll a molecules and 22 carotenoids that are involved in light harvesting and electron transfer. In eucaryotes, PSI also has a peripheral light harvesting complex I (LHCI). The role of specific chlorophylls in excitation and electron transfer are still unresolved. In particular, the role of so-called bridging chlorophylls, located between the bulk antenna and the core electron transfer chain, in the transfer of excitation energy to the reaction center are unknown. During the past funding period, site directed mutagenesis has been used to create mutants that effect the physical properties of these key chlorophylls, and to explore how this alters the function of the photosystem. Studying these mutants using ultrafast absorption spectroscopy has led to a better understanding of the process by which excitation energy is transferred from the antenna chlorophylls to the electron transfer chain chlorophylls, and what the role of connecting chlorophylls and A_0 chlorophylls is in this process. We have also used these mutants to investigate whch of the central group of six chlorophylls are involved in the primary steps of charge separation and electron transfer.

Webber, Andrew N.

2012-09-25

392

Unravelling the Excitation Spectrum of the Nucleon  

SciTech Connect

The low-energy structure of QCD lies encoded in the excited states of the nucleon, a complicated overlap of many resonances. Recent Lattice calculations have confirmed the longstanding quark model predictions of many more excited states than have been identified. Reactions that probe the spectrum are clouded by effects that dress the interactions and complicate the identification of excited levels and the interpretation of their structure. Recent theoretical work has exposed dramatic effects from such dressings. On the experimental side, new complete measurements of pseudoscalar meson photo-production are being pursued at several laboratories, where here the designation of complete refers to measurements of most if not all of the 16 possible reaction observables. This has been the focus of a series of experiments at Jefferson Lab culminating in the recently completed g9/FROST and g14/HDice runs which are now under analysis. With realistic errors, the number of observables needed to constrain the production amplitude is many more than required of a mathematical solution.

Sandorfi, Andrew M. [JLAB

2013-03-01

393

Sodium uptake and membrane excitation in Paramecium  

PubMed Central

Although the phenotypes of many membrane-excitation mutants of Paramecium are best expressed in Na+-containing solutions, little is known about the role of Na+ in membrane excitation in Paramecium. By measuring 22Na fluxes, we have shown that: (a) The total cellular Na+ content is equivalent to a cytoplasmic concentration of 3--4 mM, if the Na+ concentration is uniform throughout the cell. (b) The kinetics of Na+ uptake can be divided into a saturable Na+ uptake with an apparent Km = 0.15 mM and a nonsaturable Na+ uptake seen at higher Na+ concentrations up to 20 mM. (c) The rate of Na+ uptake in high Na+ solutions is correlated with the duration of backward swimming and membrane excitation in wild type Paramecium and the mutants fast-2 and paranoiac. (d) Na+ uptake is inhibited at 4 degrees C. From these results, we postulate that Na+ uptake is faster when the membrane is depolarized than when it is at the resting potential level. PMID:468909

1979-01-01

394

Solvation and the excited states of formamide  

NASA Astrophysics Data System (ADS)

Excited state geometries of formamide have been explored using the multiconfiguration self-consistent-field method. Optimized equilibrium geometries for the S1 and T1 states are nonplanar with the C-O and C-N bond distances substantially increased from the ground state values. The excitation energies at the ground and excited state geometries are calculated to vary dramatically with nonplanar rotation. Raman scattering from the S2 state depends on the transition moment which is shown to vary strongly with geometry. Experimental analyses that project out restricted planar conformations can fit the Raman vibrational pattern but do not inform us about the complicated energy surface for the S2 state which is a resonance embedded in a Rydberg series. Constrained optimizations are used to explore this surface and the variation in the oscillator strength with geometry. Effective fragment potentials (EFP) model the waters in the solvation models. Comparison of the EFP and all-electron structures and energy of binding shows that the EFP adequately replace the all-electron waters. The use of constrained C2v geometries for the EFP water does not significantly affect either the optimized structure or the energetics of the complex.

Krauss, M.; Webb, S. P.

1997-10-01

395

Plasmons and optical excitations in graphene rings.  

PubMed

A simple semiclassical drude-like conductivity of graphene is employed to describe plasmon excitations of graphene in the ring structures. A quasi-static self-consistent integral equation approach is performed, allowing the calculation of all the plasmon modes with different angular momentum l. Among them only the dipole modes (l = 1) will couple out to the radiation modes, which in turn can be excited optically by the plane waves, and the excitation energies as a function of the ratio of the radius of the inner hole to that of the outer ring have also been investigated. It is demonstrated that the energy of symmetric modes will monotonically decrease as the ratio rises, and the energy of antisymmetric modes does not exhibit a monotonically increasing behavior as in a three-dimensional metallic ring, but first reduces and then increases. These predictions are tested by full-wave simulations using the optical conductivity of graphene that was obtained from the random phase approximation (RPA). PMID:22971520

Wang, Weihua

2012-10-10

396

Estimates for Electromagnetically Exciting Nuclear Isomers  

NASA Astrophysics Data System (ADS)

There has been recent interest in the possible roles that nuclear isomers (both spin and shape) might play in high temperature, high neutron flux environments. Such environments are readily available in both applied physics and astrophysical settings. For example, in certain astrophysical environments, a significant change in the effective lifetimes of certain even-even nuclei can occur if their shape isomers are strongly populated. Such events can strongly effect the roles of 'waiting point' nuclei of proton-rich reactions in thermo-nuclear explosions, such as those that cause Type-I X-ray bursts. More mundane examples include the use of spin-isomers as a post-diagnostic tool for studying ignited ICF capsules or terra-based nuclear explosions. Isomers are strongly populated by nucleonic interactions. If temperatures are high enough, there is the additional possibility of populating isomers electromagnetically. Here we examine the the rates for electromagnetic excitation of several spin isomers relevant both in astrophysics and applied physics. We consider six possible electromagnetic processes, namely, photo-absorption, inverse internal conversion, inelastic electron scattering, Coulomb excitation, (?,?') and (e,e'?) reactions. We find that for plasma temperatures T ˜ 1-10 keV the electromagnetic reactions rates are negligible compared to neutron reaction rates. Thus, we conclude that these isomers are only populated by neutron excitation.

Luu, Thomas; Friar, James; Hayes, Anna

2004-10-01

397

Thermal Excitation System for Shearography (TESS)  

NASA Technical Reports Server (NTRS)

One of the most convenient and effective methods of stressing a part or structure for shearographic evaluation is thermal excitation. This technique involves heating the part, often convectively with a heat gun, and then monitoring with a shearography device the deformation during cooling. For a composite specimen, unbonds, delaminations, inclusions, or matrix cracking will deform during cooling differently than other more structurally sound regions and thus will appear as anomalies in the deformation field. However, one of the difficulties that cause this inspection to be dependent on the operator experience is the conventional heating process. Fanning the part with a heat gun by hand introduces a wide range of variability from person to person and from one inspection to the next. The goal of this research effort was to conduct research in the methods of thermal excitation for shearography inspection. A computerized heating system was developed for inspection of 0.61 m (24 in.) square panels. The Thermal Excitation System for Shearography (TESS) provides radiant heating with continuous digital measurement of the surface temperature profile to ensure repeatability. The TESS device functions as an accessory to any electronic shearography device.

Lansing, Matthew D.; Bullock, Michael W.

1996-01-01

398

DYNAMICAL ANALYSIS OF HIGHLY EXCITED MOLECULAR SPECTRA  

SciTech Connect

Spectra and internal dynamics of highly excited molecules are essential to understanding processes of fundamental importance for combustion, including intramolecular energy transfer and isomerization reactions. The goal of our program is to develop new theoretical tools to unravel information about intramolecular dynamics encoded in highly excited experimental spectra. We want to understand the formations of ''new vibrational modes'' when the ordinary normal modes picture breaks down in highly excited vibrations. We use bifurcation analysis of semiclassical versions of the effective Hamiltonians used by spectroscopists to fit complex experimental spectra. Specific molecular systems are of interest for their relevance to combustion and the availability of high-quality experimental data. Because of its immense importance in combustion, the isomerizing acetylene/vinylidene system has been the object of long-standing experimental and theoretical research. We have made significant progress in systematically understanding the bending dynamics of the acetylene system. We have begun to make progress on extending our methodology to the full bend-stretch vibrational degrees of freedom, including dynamics with multiple wells and above barrier motion, and time-dependent dynamics. For this, development of our previous methods using spectroscopic fitting Hamiltonians is needed, for example, for systems with multiple barriers.

Michael E. Kellman

2005-06-17

399

Excitation equilibria in plasmas; a classification  

NASA Astrophysics Data System (ADS)

This review gives a classification of the excitation kinetics ruled by electrons in plasmas. It is a study on the atomic state distribution function (ASDF) and its relation with underlying processes, which, for the case of an electron excitation kinetics (EEK) plasma, is merely a competition between free and bound electrons, the same particles in different circumstances. In a quasi steady state the population density of an atomic state results from production-destruction balances in equilibrium. If all balances are proper, i.e., consist of each other's inverse processes, then the ASDF is described by the Boltzmann-Saha relation. In other cases the balance will be denoted as improper, the ASDF will deviate from the equilibrium shape, but reflecting the underlying improper balances, it may give information about the plasma. Four improper balances and their impact on the ASDF are dealt with. An important feature is that improper balances are associated with particle transport. Special attention is paid to the distribution function of the excitation saturation balance in which the overpopulated bound electrons are subjected to frequent interactions with free electrons and the energy distribution of the free electrons is taken over. This distribution, denoted as the bound Maxwell distribution, is experimentally found in several ionizing plasmas. Its recombining counterpart, the deexcitation saturation balance, creates under certain conditions inversion in the ASDF, the basis for the recombination laser.

van der Mullen, J. A. M.

1990-07-01

400

College-industry alliances improving science education in Kansas  

SciTech Connect

Kansas Newman College`s investigate laboratory approach and its partnership with local industries has been motivating precollege students into science since 1990. The Vulcan Chemical Company in Wichita supported our Investigative Summer Science Program for high school juniors where we make science fun and exciting through exploration and testing of ideas, broaden their scientific interests, foster independent scholarship, and with active involvement of community scientists, make them aware of career opportunities and challenges in sciences. Upon completion, 80% to 94% of the participants became interested in pursuing science in college. Our second approach has been to encourage pre-college faculty to have their students present science projects at the annual meeting of Kansas Junior Academy of Science. The Metropolitan Life Foundation has been underwriting all the expenses for promoting participation and hosting of the annual meeting since 1987. The number of science projects/papers has increased from 11 in 1987 to 43 in 1993.

Singh, S.P.; Moore, J.; Palubicki, S. [Kansas Newman College, Wichita, KS (United States)] [and others

1994-12-31

401

69. Credit TCL. Housing of Pelton exciter impulse wheel and ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

69. Credit TCL. Housing of Pelton exciter impulse wheel and attached General Electric 60 kW exciter generator. - Battle Creek Hydroelectric System, Battle Creek & Tributaries, Red Bluff, Tehama County, CA

402

6. POWERHOUSE INTERIOR SHOWING EXCITER No. 1. HANDCONTROLLED GATE VALVE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. POWERHOUSE INTERIOR SHOWING EXCITER No. 1. HAND-CONTROLLED GATE VALVE SHOWN ON NOZZLE TO PELTON-DOBLE IMPULSE WHEEL. VIEW TO NORTHEAST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

403

12. POWERHOUSE INTERIOR SHOWING EXCITER No. 2 SMALL PELTONDOBLE IMPULSE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. POWERHOUSE INTERIOR SHOWING EXCITER No. 2 SMALL PELTON-DOBLE IMPULSE WHEEL, HAND-CONTROLLED GATE VALVE, AND NOZZLE. VIEW TO SOUTHWEST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

404

Ship Rolling Motion Subjected to Colored Noise Excitation  

E-print Network

in the probability?s view. The random differential equation of ships? rolling motion is established considering the nonlinear damping, nonlinear restoring moment, the white noise wave excitation, and the colored noise wave excitation. As an example, an ocean survey...

Jamnongpipatkul, Arada

2012-02-14

405

How a Trip to the Freezer Can Help Children Learn Science  

ERIC Educational Resources Information Center

There are lots of exciting ways for children to learn science. Going on a journey is one of them. However, when going to distant places is not possible, a virtual journey may be the next best option. Ricky, one of the authors' puppets, helps children to make virtual journeys, and this can create an exciting context for them to raise questions and…

Keogh, Brenda; Naylor, Stuart

2011-01-01

406

Libraries and Information Science: the Profession. Alternative Career Opportunities for Atmospheric, Earth, and Geo-scientists.  

NASA Astrophysics Data System (ADS)

Many graduate students, researchers and scientists may not be aware that there are other career opportunities available to them as scientists besides the traditional academic, government, industrial and private sector tracks. Subject specialists with science backgrounds are in great demand. Knowledge management and information services affiliated with science and research is an exciting and creative profession. Contributing to, finding and delivering the range of information now emerging from new and established disciplines in all formats defines Information Science and Librarianship with a multitude of opportunities. This poster will offer information to encourage students and researchers with these skills and backgrounds to consider Information and Library Science as an exciting career path.

Love, A. M.

2003-12-01

407

Charge transfer excitations from excited state Hartree-Fock subsequent minimization scheme.  

PubMed

Photoinduced charge-transfer processes play a key role for novel photovoltaic phenomena and devices. Thus, the development of ab initio methods that allow for an accurate and computationally inexpensive treatment of charge-transfer excitations is a topic that nowadays attracts a lot of scientific attention. In this paper we extend an approach recently introduced for the description of single and double excitations [M. Tassi, I. Theophilou, and S. Thanos, Int. J. Quantum Chem. 113, 690 (2013); M. Tassi, I. Theophilou, and S. Thanos, J. Chem. Phys. 138, 124107 (2013)] to allow for the description of intermolecular charge-transfer excitations. We describe an excitation where an electron is transferred from a donor system to an acceptor one, keeping the excited state orthogonal to the ground state and avoiding variational collapse. These conditions are achieved by decomposing the space spanned by the Hartree-Fock (HF) ground state orbitals into four subspaces: The subspace spanned by the occupied orbitals that are localized in the region of the donor molecule, the corresponding for the acceptor ones and two more subspaces containing the virtual orbitals that are localized in the neighborhood of the donor and the acceptor, respectively. Next, we create a Slater determinant with a hole in the subspace of occupied orbitals of the donor and a particle in the virtual subspace of the acceptor. Subsequently we optimize both the hole and the particle by minimizing the HF energy functional in the corresponding subspaces. Finally, we test our approach by calculating the lowest charge-transfer excitation energies for a set of tetracyanoethylene-hydrocarbon complexes that have been used earlier as a test set for such kind of excitations. PMID:24784248

Theophilou, Iris; Tassi, M; Thanos, S

2014-04-28

408

Charge transfer excitations from excited state Hartree-Fock subsequent minimization scheme  

SciTech Connect

Photoinduced charge-transfer processes play a key role for novel photovoltaic phenomena and devices. Thus, the development of ab initio methods that allow for an accurate and computationally inexpensive treatment of charge-transfer excitations is a topic that nowadays attracts a lot of scientific attention. In this paper we extend an approach recently introduced for the description of single and double excitations [M. Tassi, I. Theophilou, and S. Thanos, Int. J. Quantum Chem. 113, 690 (2013); M. Tassi, I. Theophilou, and S. Thanos, J. Chem. Phys. 138, 124107 (2013)] to allow for the description of intermolecular charge-transfer excitations. We describe an excitation where an electron is transferred from a donor system to an acceptor one, keeping the excited state orthogonal to the ground state and avoiding variational collapse. These conditions are achieved by decomposing the space spanned by the Hartree-Fock (HF) ground state orbitals into four subspaces: The subspace spanned by the occupied orbitals that are localized in the region of the donor molecule, the corresponding for the acceptor ones and two more subspaces containing the virtual orbitals that are localized in the neighborhood of the donor and the acceptor, respectively. Next, we create a Slater determinant with a hole in the subspace of occupied orbitals of the donor and a particle in the virtual subspace of the acceptor. Subsequently we optimize both the hole and the particle by minimizing the HF energy functional in the corresponding subspaces. Finally, we test our approach by calculating the lowest charge-transfer excitation energies for a set of tetracyanoethylene-hydrocarbon complexes that have been used earlier as a test set for such kind of excitations.

Theophilou, Iris, E-mail: i.theophilou@fz-juelich.de [Peter Grunberg Institut (PGI) Forschungszentrum Jülich, D-52425 Jülich (Germany)] [Peter Grunberg Institut (PGI) Forschungszentrum Jülich, D-52425 Jülich (Germany); Tassi, M.; Thanos, S. [Institute for Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, ‘Demokritos’ National Center for Scientific Research, 15310 Athens (Greece)] [Institute for Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, ‘Demokritos’ National Center for Scientific Research, 15310 Athens (Greece)

2014-04-28

409

Searches for excited fermions in ep collisions at HERA  

Microsoft Academic Search

Searches in ep collisions for heavy excited fermions have been performed with the ZEUS detector at HERA. Excited states of electrons and quarks have been searched for in e+p collisions at a centre-of-mass energy of 300 GeV using an integrated luminosity of 47.7 pb?1. Excited electrons have been sought via the decays e??e?, e??eZ and e???W. Excited quarks have been sought via

S. Bhadra; C. D. Catterall; W. R. Frisken; M. Khakzad; S. Magill; B. Musgrave; A. Pellegrino; J. Repond; R. Yoshida; M. C. K. Mattingly; P. Antonioli; G. Bari; M. Basile; L. Bellagamba; D. Boscherini; A. Bruni; G. Bruni; G. Cara Romeo; L. Cifarelli; F. Cindolo; A. Contin; M. Corradi; S. de Pasquale; P. Giusti; G. Iacobucci; G. Levi; A. Margotti; T. Massam; R. Nania; F. Palmonari; A. Pesci; G. Sartorelli; A. Zichichi; G. Aghuzumtsyan; I. Brock; S. Goers; H. Hartmann; E. Hilger; P. Irrgang; H.-P. Jakob; A. Kappes; U. F. Katz; R. Kerger; O. Kind; E. Paul; J. Rautenberg; H. Schnurbusch; A. Stifutkin; J. Tandler; K. C. Voss; A. Weber; H. Wieber; D. S. Bailey; N. H. Brook; J. E. Cole; B. Foster; G. P. Heath; H. F. Heath; S. Robins; E. Rodrigues; J. Scott; R. J. Tapper; M. Wing; M. Capua; A. Mastroberardino; M. Schioppa; G. Susinno; H. Y. Jeoung; J. Y. Kim; J. H. Lee; I. T. Lim; K. J. Ma; M. Y. Pac; A. Caldwell; M. Helbich; X. Liu; B. Mellado; S. Paganis; W. B. Schmidke; F. Sciulli; J. Chwastowski; A. Eskreys; J. Figiel; K. Klimek; K. Olkiewicz; M. B. Przybycien; P. Stopa; L. Zawiejski; B. Bednarek; I. Grabowska-Bold; K. Jelen; D. Kisielewska; A. M. Kowal; M. Kowal; T. Kowalski; B. Mindur; E. Rulikowska-Zarebska; L. Suszycki; D. Szuba; J. Szuba; A. Kotanski; L. A. T. Bauerdick; U. Behrens; K. Borras; V. Chiochia; J. Crittenden; D. Dannheim; K. Desler; G. Drews; A. Fox-Murphy; U. Fricke; A. Geiser; F. Goebel; P. Göttlicher; R. Graciani; T. Haas; W. Hain; G. F. Hartner; K. Hebbel; S. Hillert; U. Kötz; H. Kowalski; H. Labes; B. Löhr; R. Mankel; J. Martens; M. Martínez; M. Milite; M. Moritz; D. Notz; M. C. Petrucci; A. Polini; U. Schneekloth; F. Selonke; S. Stonjek; B. Surrow; J. J. Whitmore; R. Wichmann; G. Wolf; C. Youngman; W. Zeuner; C. Coldewey; A. Lopez-Duran Viani; A. Meyer; S. Schlenstedt; G. Barbagli; E. Gallo; P. G. Pelfer; A. Bamberger; A. Benen; N. Coppola; P. Markun; H. Raach; S. Wölfle; M. Bell; P. J. Bussey; A. T. Doyle; C. Glasman; S. W. Lee; A. Lupi; G. J. McCance; D. H. Saxon; I. O. Skillicorn; B. Bodmann; N. Gendner; U. Holm; H. Salehi; K. Wick; A. Yildirim; A. Ziegler; T. Carli; A. Garfagnini; I. Gialas; E. Lohrmann; C. Foudas; R. Gonçalo; K. R. Long; F. Metlica; D. B. Miller; A. D. Tapper; R. Walker; P. Cloth; D. Filges; M. Kuze; K. Nagano; K. Tokushuku; S. Yamada; Y. Yamazaki; A. N. Barakbaev; E. G. Boos; N. S. Pokrovskiy; B. O. Zhautykov; S. H. Ahn; S. B. Lee; S. K. Park; H. Lim; D. Son; F. Barreiro; G. García; O. González; L. Labarga; J. del Peso; I. Redondo; J. Terrón; M. Vázquez; M. Barbi; A. Bertolin; F. Corriveau; A. Ochs; S. Padhi; D. G. Stairs; M. St-Laurent; T. Tsurugai; A. Antonov; V. Bashkirov; P. Danilov; B. A. Dolgoshein; D. Gladkov; V. Sosnovtsev; S. Suchkov; R. K. Dementiev; P. F. Ermolov; Yu. A. Golubkov; I. I. Katkov; L. A. Khein; N. A. Korotkova; I. A. Korzhavina; V. A. Kuzmin; B. B. Levchenko; O. Yu. Lukina; A. S. Proskuryakov; L. M. Shcheglova; A. N. Solomin; N. N. Vlasov; S. A. Zotkin; C. Bokel; J. Engelen; S. Grijpink; E. Koffeman; P. Kooijman; E. Maddox; S. Schagen; E. Tassi; H. Tiecke; N. Tuning; J. J. Velthuis; L. Wiggers; E. de Wolf; N. Brümmer; B. Bylsma; L. S. Durkin; J. Gilmore; C. M. Ginsburg; C. L. Kim; T. Y. Ling; S. Boogert; A. M. Cooper-Sarkar; R. C. E. Devenish; J. Ferrando; J. Große-Knetter; T. Matsushita; M. Rigby; O. Ruske; M. R. Sutton; R. Walczak; R. Brugnera; R. Carlin; F. dal Corso; S. Dusini; S. Limentani; A. Longhin; A. Parenti; M. Posocco; L. Stanco; M. Turcato; L. Adamczyk; L. Iannotti; B. Y. Oh; P. R. B. Saull; W. S. Toothacker; Y. Iga; G. D'Agostini; G. Marini; A. Nigro; C. Cormack; J. C. Hart; N. A. McCubbin; C. Heusch; I. H. Park; N. Pavel; H. Abramowicz; S. Dagan; A. Gabareen; S. Kananov; A. Kreisel; A. Levy; T. Abe; T. Fusayasu; T. Kohno; K. Umemori; T. Yamashita; R. Hamatsu; T. Hirose; M. Inuzuka; S. Kitamura; K. Matsuzawa; T. Nishimura; M. Arneodo; N. Cartiglia; R. Cirio; M. Costa; M. I. Ferrero; S. Maselli; V. Monaco; C. Peroni; M. Ruspa; R. Sacchi; A. Solano; A. Staiano; D. C. Bailey; C.-P. Fagerstroem; R. Galea; T. Koop; G. M. Levman; J. F. Martin; A. Mirea; A. Sabetfakhri; J. M. Butterworth; C. Gwenlan; R. Hall-Wilton; M. E. Hayes; E. A. Heaphy; T. W. Jones; M. S. Lightwood; B. J. West; J. Ciborowski; R. Ciesielski; G. Grzelak; R. J. Nowak; J. M. Pawlak; B. Smalska; T. Tymieniecka; A. Ukleja; J. Ukleja; J. A. Zakrzewski; A. F. Zarnecki; M. Adamus; P. Plucinski; J. Sztuk; Y. Eisenberg; L. K. Gladilin; D. Hochman; U. Karshon; J. Breitweg; D. Chapin; R. Cross; D. Kçira; S. Lammers; D. D. Reeder; A. A. Savin; W. H. Smith; A. Deshpande; S. Dhawan; V. W. Hughes; P. B. Straub; S. Menary

2002-01-01

410

Simultaneous two-photon excitation of photodynamic therapy agents  

SciTech Connect

The spectroscopic and photochemical properties of several photosensitive compounds are compared using conventional single-photon excitation (SPE) and simultaneous two-photon excitation (TPE). TPE is achieved using a mode-locked titanium:sapphire laser, the near infrared output of which allows direct promotion of non-resonant TPE. Excitation spectra and excited state properties of both type 1 and type 2 photodynamic therapy (PDT) agents are examined.

Wachter, E.A.; Fisher, W.G. [Oak Ridge National Lab., TN (United States)]|[Photogen, Inc., Knoxville, TN (United States); Partridge, W.P. [Oak Ridge National Lab., TN (United States); Dees, H.C. [Photogen, Inc., Knoxville, TN (United States); Petersen, M.G. [Univ. of Tennessee, Knoxville, TN (United States). College of Veterinary Medicine

1998-01-01

411

Active control of tensegrity structures under random excitation  

Microsoft Academic Search

In this paper we consider vibration control of tensegrity structures under stationary and nonstationary random excitations. These excitations may be representative of many physical loading conditions, such as earthquake, wind, aerodynamic and acoustic excitations. The optimal control theory based on H2 and \\\\mathrm {H}_{\\\\infty } controller with full state and limited state feedback is used for the control. The response

M. Ganesh Raja; S. Narayanan

2007-01-01

412

Piezoelectric Rayleigh Wave Excitation by Bulk Wave Scattering  

Microsoft Academic Search

The excitation of a Rayleigh surface wave on a piezoelectric crystal by the scattering of bulk waves from strips deposited on the crystal's surface is considered. Using small scatterer approximations to obtain a lower limit for the strength of excitation that can be obtained by the scattering method, the Rayleigh wave excitation resulting from the mass of the deposited strips

H. L. Bertoni; A. N. Broers; E. G. H. Lean; R. V. Pole; M Hatzakis; D. Cul; C. G. Powell

1969-01-01

413

The mechanism of electronic excitation in the bacterial bioluminescent reaction  

NASA Astrophysics Data System (ADS)

The current state of the problem of formation of the electron-excited product in the chemiluminescent reaction that underlies the bacterial luminescence is analysed. Various schemes of chemical transformations capable of producing a bacterial bioluminescence emitter are presented. The problem of excitation of secondary emitters is considered; two possible mechanisms of their excitation are analysed.

Nemtseva, E. V.; Kudryasheva, N. S.

2007-01-01

414

Alinement and Modeling of Hanford Excitation Control for System Damping  

Microsoft Academic Search

The alinement of speed excitation supplementary control for each of the two Hanford 430 MW nuclear steam turbine-generator units was readily accomplished through field testing. Off-line frequency response tests of the supplementary control units, voltage regulators and exciters and frequency and step response test of the excitation system provided data used to develop a dynamic simulation model of the Hanford

Edward Warchol; Ferber Schleif; William Gish; John Church

1971-01-01

415

Excitation of Central Nervous System Neurons by Nonuniform Electric Fields  

Microsoft Academic Search

The goal of this study was to determine which neural elements are excited by microstimulation of the central nervous system. A cable model of a neuron including an axon, initial segment, axon hillock, soma, and simplified dendritic tree was used to study excitation with an extracellular point source electrode. The model reproduced a wide range of experimentally documented extracellular excitation

Cameron C. McIntyre; Warren M. Grill

1999-01-01

416

0+Excited States in Nuclei: Critical Signatures of Structure  

NASA Astrophysics Data System (ADS)

It is emerging from data that excited 0+ states in nuclei are critical signatures of structure. Some examples of excited 0+ states that are reasonably well understood are followed by details, from recent experimental work, of excited 0+ states that are causing major reassessment of some models.

Wood, J. L.

2015-11-01

417

Spectroscopy, reaction, and photodissociation in highly vibrationally excited molecules  

SciTech Connect

Highly vibrationally excited molecules often control the course of chemical reactions in the atmosphere, combustion, plasmas, and many other environments. The research described in this Progress Report uses laser excitation and interrogation techniques to study and control the dynamics of highly vibrationally excited molecules. In particular, they show that it is possible to unravel the details and influence the course of photodissociation and bimolecular reaction. The experiments use laser excitation of overtone vibrations to prepare highly vibrationally excited molecules, frequently with single quantum state resolution, and laser spectroscopy to monitor the subsequent behavior of the excited molecule. We have studied the vibrationally mediated photodissociation and the bond- and state-selected bimolecular reaction of highly vibrationally excited molecules. In the first process, one photon creates a highly excited molecule, a second photon from another laser dissociates it, and light from a third laser detects the population of individual product quantum states. This approach allows us to explore otherwise inaccessible regions of the ground and excited state potential energy surface and, by exciting to the proper regions of the surface, to control the breaking of a selected chemical bond. In the second process, the highly vibrationally excited molecule reacts with an atom formed either in a microwave discharge or by photolysis and another laser interrogates the products. We have used this approach to demonstrate mode- and bond-selected bimolecular reactions in which the initial excitation controls the subsequent chemistry. 30 refs., 8 figs.

Not Available

1991-01-01

418

Three Steps for Better Reading in Science: Before, During, and After  

NSDL National Science Digital Library

It's exciting to have a beautiful new science textbook--if students can read it! Unfortunately, many students can't read their science textbook unassisted. Since reading and critical thinking skills are an integral component of science, teachers must provide a structure that brings the material to the students' level and engages them with the text. This model for literacy instruction in the science classroom includes strategies that students can employ before, during, and after reading.

Walton, Susan

2006-12-01

419

Enhanced production of excited neutrals following core-to-Rydberg excitation in molecules: SiCl4  

Microsoft Academic Search

Using monochromatized synchrotron radiation in the range 103 to 112 eV we have monitored the dispersed UV\\/optical fluorescence resulting from excitation of a Si 2p electron in SiCl4. The main features in the fluorescence spectrum have been identified as emission from the SiCl4+C state and from excited Si atoms. Features in the fluorescence excitation spectra are assigned to excitation of

R A Rosenberg; C-R Wen; K Tan; J-M Chen

1990-01-01

420

Enhanced production of excited neutrals following core-to-Rydberg excitation in molecules: SiCl4  

Microsoft Academic Search

Using monochromatized synchrotron radiation in the range 103 to 112 eV we have monitored the dispersed UV\\/optical fluorescence resulting from excitation of a Si 2p electron in SiCl4. The main features in the fluorescence spectrum have been identified as emission from the SiCl4+ C state and from excited Si atoms. Features in the fluorescence excitation spectra are assigned to excitation

R. A. Rosenberg; C.-R. Wen; K. Tan; J.-M. Chen

1990-01-01

421

Science Project  

NSDL National Science Digital Library

The Science Project website welcomes you to "the world's largest web site for Science Project ideas, information and support." Students can search for ideas by level: primary (e.g. Make a Volcano), elementary (e.g. Fluorescent Lights), intermediate (e.g. pendulums), and senior (e.g. Study of efficient home insulation). Senior project ideas cover the following topic areas: Biology, Engineering, Physical Science, Earth Science/Meteorology, Environmental Science, Computer Science, and Chemistry. The ideas are accessible for free without registration, but "only members can get support and access the members section for more project details." (Unfortunately, this does favor those able to pay -- Basic membership is $25/year and Advanced membership is $150/year, but a trial membership for 90 days is $10.) Opportunities for teachers, scientists and schools are also described within Membership Info.

422

Service Science  

Microsoft Academic Search

This paper is a first exploration of the relationship between service science and Grid computing. Service science is the study\\u000a of value co-creation interactions among entities, known as service systems. Within the emerging service science community,\\u000a service is often defined as the application of competences (resources) for the benefit of another. Grid computing is the study\\u000a of resource sharing among

Jim Spohrer; Laura C. Anderson; Norman J. Pass; Tryg Ager; Daniel Gruhl

2008-01-01

423

Science Insight  

NSDL National Science Digital Library

The Science Policy Research Unit (SPRU) for the British Council produces Science Insight to keep scientists informed about recent events and news in science and technology. Information is divided into twelve categories, spanning a variety of news topics, such as research and energy and environment policy, and resources including new publications and the internet. The site includes links to its own information sources, as well.

1998-01-01

424

Science Activities  

NSDL National Science Digital Library

This collection of K-12 activities covers the following science content areas: bioscience, communications, computers, earth and physical sciences, energy, math, oceanography, space, and transportation. Specific activities that may be classified under Earth system science include: Bringing the Greenhouse Effect Down to Earth, The Greenhouse Effect in a Jar, Slick Sea Spills, Ocean in a Bottle, People Changing the Atmosphere, Frozen Erosion, and The Satellite Delay Relay. Also included are references to additional resources and information on how to order activity kits.

425

Deconstructing science  

NASA Astrophysics Data System (ADS)

In this paper I expand on the premises of Jesse Bazzul's thesis in his paper, Neoliberal ideology, global capitalism, and science education: engaging the question of subjectivity, exploring the implications of the ideologies within the culturally emerging logic of science exposes the incommensurability of intents and purposes in its methods and epistemology. I argue that science needs to acknowledge the subjectivity at its core to make space for non-absolute agents and new fields of study.

Trifonas, Peter Pericles

2012-12-01

426

Professionals and Emerging Scientists Sharing Science  

NASA Technical Reports Server (NTRS)

The Year of the Solar System (YSS) celebration begins in the fall of 2010. As YSS provides a means in which NASA can inspire members of the public about exciting missions to other worlds in our solar system, it is important to remember these missions are about the science being conducted and new discoveries being made. As part of the Year of the Solar System, Astromaterials Research and Exploration Science (ARES) Education, at the NASA Johnson Space Center, will infuse the great YSS celebration within the Expedition Earth and Beyond Program. Expedition Earth and Beyond (EEAB) is an authentic research program for students in grades 5-14 and is a component of ARES Education. Students involved in EEAB have the opportunity to conduct and share their research about Earth and/or planetary comparisons. ARES Education will help celebrate this exciting Year of the Solar System by inviting scientists to share their science. Throughout YSS, each month will highlight a topic related to exploring our solar system. Additionally, special mission events will be highlighted to increase awareness of the exciting missions and exploration milestones. To bring this excitement to classrooms across the nation, the Expedition Earth and Beyond Program and ARES Education will host classroom connection events in which scientists will have an opportunity to share discoveries being made through scientific research that relate to the YSS topic of the month. These interactive presentations will immerse students in some of the realities of exploration and potentially inspire them to conduct their own investigations. Additionally, scientists will share their own story of how they were inspired to pursue a STEM-related career that got them involved in exploration. These career highlights will allow students to understand and relate to the different avenues that scientists have taken to get where they are today. To bring the sharing of science full circle, student groups who conduct research by participating in Expedition Earth and Beyond, will also have the opportunity to virtually share their research. These virtual team presentations will allow these emerging scientists to celebrate their own exploration, and in doing so, contribute to the excitement of the Year of the Solar System. As the public joins NASA in the celebration of YSS, students across the nation will not only be excited by the science and discoveries being made, but will prime themselves with experience to perhaps someday become the new leaders in science, discovery, and NASA.

Graff, P. V.; Allen, J. S.; Tobola, K.

2010-01-01

427

Science Fair  

NSDL National Science Digital Library

Your task is to design a science fair project by choosing from a list of questions that I have provided. The questions will narrow down your topic to a specific area in science, however the ultimate topic of your project is up to you! Make sure to pick an area of science that you are interested in, this should be fun! Enjoy! Guidelines For The Project: You may work in pairs, or by yourself. There are to be no more than two people working together on a single project. Partners must be in the same period science class. Research will be done on the project, a works cited page must also ...

Ms. Baumes

2008-05-15

428

Sublime Science  

NSDL National Science Digital Library

One of the shortcomings in most efforts to integrate art and science is that many of us have a shallow understanding of art, which inevitably leads to shallow connections between art and science. Coloring drawings of planets, building sculptures of volcanoes, and decorating scientific diagrams are fine activities, but they do not link science and art in powerful ways. One way to more deeply connect art and science is to consider art in its more broad form--aesthetics, and in this case, the sublime.

Mark Girod

2007-02-01

429

Standoff alpha radiation detection via excited state absorption of air  

SciTech Connect

A standoff alpha radiation detection technique based on the physical mechanism of excited state absorption of air molecules was explored and is presented in this paper. Instead of directly detecting the radiation via measuring the intensity of radiation induced air fluorescence, the radiation is detected via the excited state absorption of alpha radiation excited/ionized air molecules. Both theoretical analyses and experimental verifications were conducted. The experimental results confirmed that the radiation could be detected via excited state absorption of radiation excited/ionized air molecules at a 10 m standoff distance, which was consistent with the theoretical analyses.

Yao, Jimmy; Yin, Stuart Shizhuo [Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)] [Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Brenizer, Jack [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)] [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Hui, Rongqing [Department of Electrical Engineering and Computer Science, The University of Kansas, Lawrence, Kansas 66045 (United States)] [Department of Electrical Engineering and Computer Science, The University of Kansas, Lawrence, Kansas 66045 (United States)

2013-06-24

430

Minimal excitation states of electrons in one-dimensional wires.  

PubMed

A strategy is proposed to excite particles from a Fermi sea in a noise-free fashion by electromagnetic pulses with realistic parameters. We show that by using quantized pulses of simple form one can suppress the particle-hole pairs which are created by a generic excitation. The resulting many-body states are characterized by one or several particles excited above the Fermi surface accompanied by no disturbance below it. These excitations carry charge which is integer for noninteracting electron gas and fractional for Luttinger liquid. The operator algebra describing these excitations is derived, and a method of their detection which relies on noise measurement is proposed. PMID:17025911

Keeling, J; Klich, I; Levitov, L S

2006-09-15

431

The photodissociation and reaction dynamics of vibrationally excited molecules  

SciTech Connect

This research determines the nature of highly vibrationally excited molecules, their unimolecular reactions, and their photodissociation dynamics. The goal is to characterize vibrationally excited molecules and to exploit that understanding to discover and control their chemical pathways. Most recently the author has used a combination of vibrational overtone excitation and laser induced fluorescence both to characterize vibrationally excited molecules and to study their photodissociation dynamics. The author has also begun laser induced grating spectroscopy experiments designed to obtain the electronic absorption spectra of highly vibrationally excited molecules.

Crim, F.F. [Univ. of Wisconsin, Madison (United States)

1993-12-01

432

Dynamic Characteristics of Excited Atomic Systems  

NASA Astrophysics Data System (ADS)

The dynamics of excited atom interactions with other atoms, which often lead to associative ionization, is largely governed by stochastic diffusion of the valence electron through Rydberg states prior to the ionization. Such processes are associated with random changes of the energy state of the highly excited electron, and they are likely to influence the nuclear dynamics, especially at subthermal collision energies. Possibilities of manipulation of the chaotic dynamics of Rydberg states require a detailed exploration. For an electron in a given Rydberg state moving in a microwave field, which can be generated via interaction with another atom or molecule, there exists critical field strength, above which motion of the electron in the energy space is chaotic. Recently a way to block the dynamic chaos regime was shown, if a given Rydberg state is located somewhat above the middle between the two other states with the orbital quantum number differing by one, whereby level shifts can be controlled by employing Stark/Zeeman shifts in external DC electric/magnetic fields. The stochastic effects in collisions involving Rydberg particles, in which the initial and final reaction channels are connected via intermediate highly excited collision complexes with multiple crossings of energy levels, can be treated using the dynamic chaos approach (Chirikov criterion, Standard and Keppler mapping of time evolution of the Rydberg electron, solution of the Fokker-Plank- and Langevin-type of equations, etc.). Such approach to obtaining dynamics characteristics is a natural choice, since the treatment of Rydberg electron dynamics as a kind of diffusion process allowing one to bypass the multi-level-crossing problem, which can hardly be solved by conventional quantum chemistry methods.

Bezuglov, N. N.; Dimitrijevic, M. S.; Klyucharev, A. N.; Mihajlov, A. A.

2014-12-01

433

Studies of Excitation Mechanisms in Europium Doped Gallium Nitride under Simultaneous Electron Beam and Laser Excitations  

NASA Astrophysics Data System (ADS)

Europium (Eu) ions are capable of absorbing energy from electron hole pairs (EHPs) resulting in an excitation of the electrons in their 4f shells and subsequently, a red emission. To this end, Eu ions can be doped in gallium nitride (GaN) to produce a red-emitting LED. Identifying and capitalizing on the most efficient energy transfer pathway for EHP excitation of Eu ions is crucial for the success of these LEDs. However, this process is still not well understood. Therefore, in order to better understand the EHP energy transfer, a new experimental setup has been developed combining the complimentary techniques of photoluminescence (PL) and cathodoluminescence (CL). In this setup, simultaneous direct optical excitation and EHP excitation of rare earth (RE) ions in GaN has been achieved. This setup is a fiber based confocal optical microscope that operates inside of a JEOL 6400 scanning electron microscope (SEM) chamber enabling the excitation of a sample either by a laser or electron beam. The module is attached to a cryogenic stage (Oxford) allowing temperature dependent measurements. The illumination and collection fibers operate as effective pinholes providing, in combination with a microscope objective (NA=0.3), high spatial resolution (˜2 mum) and excellent collection efficiency. The high spatial resolution ensures that the light collected from the sample is in a region of optimal laser and electron beam overlap. The experimental techniques performed show that the EHP excitation pathway is affected by different growth parameters, V-III ratios, and Mg co-dopants as these alter the environment surrounding the RE ion (i.e. incorporation site). In particular, site-selective measurements have been used to identify several Eu incorporation sites. Combining this technique with CL reveals that some sites absorb energy from EHPs more efficiently than others. Additionally, the combined excitation techniques show that there is a trapping mechanism associated with the excitation of Eu ions by EHPs, and that there are several electro-optically inactive Eu ions when doped in GaN. The experiments reported in this work represent only a small portion of the possibilities unlocked by this instrument. For example, in addition to the combination of PL and CL studies, structural changes induced by the electron beam may be observed using Raman spectroscopy.

Poplawsky, Jonathan D.

434

New laser excitation method for modal analysis of microstructure  

NASA Astrophysics Data System (ADS)

A novel impulse laser excitation technique to determine the dynamic response of micro-electro-mechanical systems (MEMS) has been investigated. During the laser excitation experiments, MEMS structures are excited by the wide-band impact force created by the laser-target interaction, and Laser Doppler Vibrometer (LDV) is introduced to measure the vibration velocity of MEMS structures. A distinguishing characteristic of the methodology is that both the excitation and measurement are non-contact, which is especially suitable for the testing of MEMS microstructures that are not easily accessible. This novel excitation method and MEMS modal analysis system are verified by experiments on various cantilever beams. The results show that the laser excitation is capable of exciting the first three modes of cantilevers.

Xiong, Liangcai; Zhou, Quansheng; Wu, You; Chen, Peng

2015-01-01

435

Nonlinear Optical Excitations in Carbon and BN Nanotubes  

NASA Astrophysics Data System (ADS)

This talk will focus on the coherent control of electronic excitations on carbon and boron-nitride nanotubes using nonlinear optical excitation. By varying the relative phases, frequencies and polarizations of incident optical fields one can control the symmetries of the optically excited states and the momentum space distribution of the photoexcited electrons. For carbon nanotubes we study the interference of amplitudes for one photon (2?) and two photon (?) excitations between the ground and excited states which produces a polar asymmetry in the excited carrier density and therefore a net current along the tube axis. For BN nanotubes we study the shift current induced by interband optical excitations. We analyze the spatial symmetry of the shift current in terms the chiral index and hence the ground state electric polarization of the heteropolar tube. This work was carried out in collaboration with P. Kral and D. Tomanek

Mele, E. J.

2001-03-01

436

Excited light isoscalar mesons from lattice QCD  

SciTech Connect

I report a recent lattice QCD calculation of an excited spectrum of light isoscalar mesons, something that has up to now proved challenging for lattice QCD. With novel techniques we extract an extensive spectrum with high statistical precision, including spin-four states and, for the first time, light isoscalars with exotic quantum numbers. In addition, the hidden flavour content of these mesons is determined, providing a window on annihilation dynamics in QCD. I comment on future prospects including applications to the study of resonances.

Christopher Thomas

2011-07-01

437

Excitations in superfluids of atoms and polaritons  

E-print Network

Helium [7, 8] and now is referred to as Gross-Pitaevskii equation (GPE). Solutions to the NLSE or GPE include such phe- nomena as solitons, quantum vortices or quantum vortex rings. These elementary and 9 topologically stable excitations are spatially... of oppositely charged spin-half particles in a semiconductor held together by an effective Coulomb force between them [28] as the energy to form a pair is lower than a free electron and a free hole. They interact with light fields [29] and can form...

Pinsker, Florian

2014-11-11

438

Leptonic partial widths of the excited ? states  

NASA Astrophysics Data System (ADS)

The resonance parameters of the excited ?-family resonances, namely, the ?(4040), ?(4160), and ?(4415), were determined by fitting the R values measured by experiments. It is found that the previously reported leptonic partial widths of these states were merely one possible solution among a four-fold ambiguity. By fitting the most precise experimental data on the R values measured by the BES collaboration, this work presents all four sets of solutions. These results may affect the interpretation of the charmonium and charmonium-like states above 4GeV/c2.

Mo, X. H.; Yuan, C. Z.; Wang, P.

2010-10-01

439

Excited intruder states in {sup 32}Mg  

SciTech Connect

The low energy level structure of N=20 {sup 32}Mg obtained via {beta}-delayed {gamma} spectroscopy is reported. The level structure of {sup 32}Mg is found to be completely dominated by intruders. An inversion between the 1p-1h and 3p-3h states is observed for the negative parity states, similar to the 0p-0h and 2p-2h inversion for the positive parity states in these N{approx}20 nuclei. The intruder excited states, both positive and negative parity, are reasonably explained by Monte Carlo shell model calculations, which suggest a shrinking N=20 shell gap with decreasing Z.

Tripathi, Vandana; Tabor, S. L.; Bender, P.; Hoffman, C. R.; Lee, Sangjin; Pepper, K.; Perry, M.; Utsuno, Y.; Otsuka, T. [Department of Physics, Florida State University, Tallahassee, Florida 32306 (United States); Advanced Science Research Centre, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Department of Physics and Center for Nuclear Study, University of Tokyo, Hongo, Tokyo 113-0033, Japan and RIKEN, Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Mantica, P. F.; Pinter, J. S.; Stoker, J. B. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Chemistry, Michigan State University, East Lansing, Michigan 48824 (United States); Cook, J. M. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Physics, Michigan State University, East Lansing, Michigan 48824 (United States); Pereira, J.; Weisshaar, D. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States)

2008-03-15

440

Magnetic excitations in nuclei with neutron excess  

E-print Network

The excitation of the $1^+$, $2^-$ and $3^+$ modes in $^{16}$O, $^{22}$O, $^{24}$O, $^{28}$O, $^{40}$Ca, $^{48}$Ca, $^{52}$Ca and $^{60}$Ca nuclei is studied with self-consistent random phase approximation calculations. Finite-range interactions of Gogny type, containing also tensor-isospin terms, are used. We analyze the evolution of the magnetic resonances with the increasing number of neutrons, the relevance of collective effects, the need of a correct treatment of the continuum and the role of the tensor force.

G. Co'; V. De Donno; M. Anguiano; A. M. Lallena

2012-03-13

441

On rotational solutions for elliptically excited pendulum  

E-print Network

The author considers the planar rotational motion of the mathematical pendulum with its pivot oscillating both vertically and horizontally, so the trajectory of the pivot is an ellipse close to a circle. The analysis is based on the exact rotational solutions in the case of circular pivot trajectory and zero gravity. The conditions for existence and stability of such solutions are derived. Assuming that the amplitudes of excitations are not small while the pivot trajectory has small ellipticity the approximate solutions are found both for high and small linear damping. Comparison between approximate and numerical solutions is made for different values of the damping parameter.

Anton O. Belyakov

2010-12-30

442

Observation of Excited ?b0 Baryons  

NASA Astrophysics Data System (ADS)

Using pp collision data corresponding to 1.0fb-1 integrated luminosity collected by the LHCb detector, two narrow states are observed in the ?b0?+?- spectrum with masses 5911.97±0.12(stat)±0.02(syst)±0.66(?b0mass)MeV/c2 and 5919.77±0.08(stat)±0.02(syst)±0.66(?b0mass)MeV/c2. The significances of the observations are 5.2 and 10.2 standard deviations, respectively. These states are interpreted as the orbitally excited ?b0 baryons, ?b*0(5912) and ?b*0(5920).

Aaij, R.; Abellan Beteta, C.; Adametz, A.; Adeva, B.; Adinolfi, M.; Adrover, C.; Affolder, A.; Ajaltouni, Z.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Alvarez Cartelle, P.; Alves, A. A., Jr.; Amato, S.; Amhis, Y.; Anderson, J.; Appleby, R. B.; Aquines Gutierrez, O.; Archilli, F.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Bachmann, S.; Back, J. J.; Balagura, V.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Bates, A.; Bauer, C.; Bauer, Th.; Bay, A.; Beddow, J.; Bediaga, I.; Belogurov, S.; Belous, K.; Belyaev, I.; Ben-Haim, E.; Benayoun, M.; Bencivenni, G.; Benson, S.; Benton, J.; Bernet, R.; Bettler, M.-O.; van Beuzekom, M.; Bien, A.; Bifani, S.; Bird, T.; Bizzeti, A.; Bjørnstad, P. M.; Blake, T.; Blanc, F.; Blanks, C.; Blouw, J.; Blusk, S.; Bobrov, A.; Bocci, V.; Bondar, A.; Bondar, N.; Bonivento, W.; Borghi, S.; Borgia, A.; Bowcock, T. J. V.; Bozzi, C.; Brambach, T.; van den Brand, J.; Bressieux, J.; Brett, D.; Britsch, M.; Britton, T.; Brook, N. H.; Brown, H.; Büchler-Germann, A.; Burducea, I.; Bursche, A.; Buytaert, J.; Cadeddu, S.; Callot, O.; Calvi, M.; Calvo Gomez, M.; Camboni, A.; Campana, P.; Carbone, A.; Carboni, G.; Cardinale, R.; Cardini, A.; Carson, L.; Carvalho Akiba, K.; Casse, G.; Cattaneo, M.; Cauet, Ch.; Charles, M.; Charpentier, Ph.; Chen, P.; Chiapolini, N.; Chrzaszcz, M.; Ciba, K.; Cid Vidal, X.; Ciezarek, G.; Clarke, P. E. L.; Clemencic, M.; Cliff, H. V.; Closier, J.; Coca, C.; Coco, V.; Cogan, J.; Cogneras, E.; Collins, P.; Comerma-Montells, A.; Contu, A.; Cook, A.; Coombes, M.; Corti, G.; Couturier, B.; Cowan, G. A.; Craik, D.; Currie, R.; D'Ambrosio, C.; David, P.; David, P. N. Y.; De Bonis, I.; De Bruyn, K.; De Capua, S.; De Cian, M.; De Miranda, J. M.; De Paula, L.; De Simone, P.; Decamp, D.; Deckenhoff, M.; Degaudenzi, H.; Del Buono, L.; Deplano, C.; Derkach, D.; Deschamps, O.; Dettori, F.; Dickens, J.; Dijkstra, H.; Diniz Batista, P.; Domingo Bonal, F.; Donleavy, S.; Dordei, F.; Dosil Suárez, A.; Dossett, D.; Dovbnya, A.; Dupertuis, F.; Dzhelyadin, R.; Dziurda, A.; Dzyuba, A.; Easo, S.; Egede, U.; Egorychev, V.; Eidelman, S.; van Eijk, D.; Eisele, F.; Eisenhardt, S.; Ekelhof, R.; Eklund, L.; El Rifai, I.; Elsasser, Ch.; Elsby, D.; Esperante Pereira, D.; Falabella, A.; Färber, C.; Fardell, G.; Farinelli, C.; Farry, S.; Fave, V.; Fernandez Albor, V.; Ferro-Luzzi, M.; Filippov, S.; Fitzpatrick, C.; Fontana, M.; Fontanelli, F.; Forty, R.; Francisco, O.; Frank, M.; Frei, C.; Frosini, M.; Furcas, S.; Gallas Torreira, A.; Galli, D.; Gandelman, M.; Gandini, P.; Gao, Y.; Garnier, J.-C.; Garofoli, J.; Garra Tico, J.; Garrido, L.; Gascon, D.; Gaspar, C.; Gauld, R.; Gauvin, N.; Gersabeck, M.; Gershon, T.; Ghez, Ph.; Gibson, V.; Gligorov, V. V.; Göbel, C.; Golubkov, D.; Golutvin, A.; Gomes, A.; Gordon, H.; Grabalosa Gándara, M.; Graciani Diaz, R.; Granado Cardoso, L. A.; Graugés, E.; Graziani, G.; Grecu, A.; Greening, E.; Gregson, S.; Grünberg, O.; Gui, B.; Gushchin, E.; Guz, Yu.; Gys, T.; Hadjivasiliou, C.; Haefeli, G.; Haen, C.; Haines, S. C.; Hampson, T.; Hansmann-Menzemer, S.; Harnew, N.; Harnew, S. T.; Harrison, J.; Harrison, P. F.; Hartmann, T.; He, J.; Heijne, V.; Hennessy, K.; Henrard, P.; Hernando Morata, J. A.; van Herwijnen, E.; Hicks, E.; Hoballah, M.; Hopchev, P.; Hulsbergen, W.; Hunt, P.; Huse, T.; Huston, R. S.; Hutchcroft, D.; Hynds, D.; Iakovenko, V.; Ilten, P.; Imong, J.; Jacobsson, R.; Jaeger, A.; Jahjah Hussein, M.; Jans, E.; Jansen, F.; Jaton, P.; Jean-Marie, B.; Jing, F.; John, M.; Johnson, D.; Jones, C. R.; Jost, B.; Kaballo, M.; Kandybei, S.; Karacson, M.; Karbach, T. M.; Keaveney, J.; Kenyon, I. R.; Kerzel, U.; Ketel, T.; Keune, A.; Khanji, B.; Kim, Y. M.; Knecht, M.; Kochebina, O.; Komarov, I.; Koopman, R. F.; Koppenburg, P.; Korolev, M.; Kozlinskiy, A.; Kravchuk, L.; Kreplin, K.; Kreps, M.; Krocker, G.; Krokovny, P.; Kruse, F.; Kruzelecki, K.; Kucharczyk, M.; Kudryavtsev, V.; Kvaratskheliya, T.; La Thi, V. N.; Lacarrere, D.; Lafferty, G.; Lai, A.; Lambert, D.; Lambert, R. W.; Lanciotti, E.; Lanfranchi, G.; Langenbruch, C.; Latham, T.; Lazzeroni, C.; Le Gac, R.; van Leerdam, J.; Lees, J.-P.; Lefèvre, R.; Leflat, A.; Lefrançois, J.; Leroy, O.; Lesiak, T.; Li, L.; Li, Y.; Li Gioi, L.; Lieng, M.; Liles, M.; Lindner, R.; Linn, C.; Liu, B.; Liu, G.; von Loeben, J.; Lopes, J. H.; Lopez Asamar, E.; Lopez-March, N.; Lu, H.; Luisier, J.; Mac Raighne, A.; Machefert, F.; Machikhiliyan, I. V.; Maciuc, F.; Maev, O.; Magnin, J.; Malde, S.; Mamunur, R. M. D.; Manca, G.; Mancinelli, G.; Mangiafave, N.; Marconi, U.; Märki, R.; Marks, J.; Martellotti, G.; Martens, A.; Martin, L.; Martín Sánchez, A.; Martinelli, M.; Martinez Santos, D.; Massafferri, A.; Mathe, Z.; Matteuzzi, C.; Matveev, M.; Maurice, E.

2012-10-01

443

Excitation of surface waves in an orotron  

NASA Astrophysics Data System (ADS)

Results of a theoretical analysis of the density of starting currents of surface waves in an orotron for different electron-beam voltages and different periods of the comb-type periodic structure are presented with reference to the design of backward-wave tubes. Good agreement is found between the theoretical results and experimental data on the voltage dependences of the starting currents of orotron oscillations and surface-wave starting currents. It is concluded that the results obtained can be used to control the excitation of surface waves in orotrons and maintain the stable operation of orotrons in the appropriate high-frequency range.

Rusin, F. S.; Kostromin, V. P.

1985-05-01

444

Singleparticle excitations in sup 89 Y  

Microsoft Academic Search

Inelastic-electron-scattering cross sections have been measured for the first three excitations in ⁸⁹Y at forward angles for momentum transfers of 1.25>{ital q}>3.01 fm⁻¹ and at 180° for 0.72>{ital q}>2.67 fm⁻¹. Transition charge and current densities extracted in a Fourier-Bessel analysis of all existing cross sections show considerable departures from the single-particle model. The inclusion of core polarization from the operator

J. E. Wise; F. W. Hersman; J. H. Heisenberg; T. E. Milliman; J. P. Connelly; J. R. Calarco; C. N. Papanicolas

1990-01-01

445

Collective Excitations in Electron-Hole Bilayers  

SciTech Connect

We report a combined analytic and molecular dynamics analysis of the collective mode spectrum of a bipolar (electron-hole) bilayer in the strong coupling classical limit. A robust, isotropic energy gap is identified in the out-of-phase spectra, generated by the combined effect of correlations and of the excitation of the bound dipoles. In the in-phase spectra we identify longitudinal and transverse acoustic modes wholly maintained by correlations. Strong nonlinear generation of higher harmonics of the fundamental dipole oscillation frequency and the transfer of harmonics between different modes is observed.

Kalman, G. J. [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States); Hartmann, P.; Donko, Z. [Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Golden, K. I. [Department of Mathematics and Statistics and Department of Physics, University of Vermont, Burlington, Vermont 05401 (United States)

2007-06-08

446

On rotational solutions for elliptically excited pendulum  

NASA Astrophysics Data System (ADS)

The author considers the planar rotational motion of the mathematical pendulum with its pivot oscillating both vertically and horizontally, so the trajectory of the pivot is an ellipse close to a circle. The analysis is based on the exact rotational solutions in the case of circular pivot trajectory and zero gravity. The conditions for existence and stability of such solutions are derived. Assuming that the amplitudes of excitations are not small while the pivot trajectory has small ellipticity the approximate solutions are found both for high and small linear dampings. Comparison between approximate and numerical solutions is made for different values of the damping parameter.

Belyakov, Anton O.

2011-06-01

447

Photo-Excited Charge Collection Spectroscopy  

NASA Astrophysics Data System (ADS)

Important performance factors and basic device physics of organic or inorganic-channel thin-film transistors (TFTs) are addressed before introducing the photo-excited charge collection spectroscopy (PECCS), so that systematic and in-depth understanding on the device stability issues may be naturally drawn in focus. Device architecture, device physics, and general stability issues in TFT (or field-effect transistor) are thus introduced in the initial sections, and in the last section our photon-probing technique is explained along with its own device physics.

Im, Seongil; Chang, Youn-Gyoung; Kim, Jae Hoon

448

Two photon excitation of atomic oxygen  

NASA Technical Reports Server (NTRS)

A standard perturbation expansion in the atom-radiation field interaction is used to calculate the two photon excitation cross section for 1s(2) 2s(2) 2p(4) p3 to 1s(2) 2s(2) 2p(3) (s4) 3p p3 transition in atomic oxygen. The summation over bound and continuum intermediate states is handled by solving the equivalent inhomogeneous differential equation. Exact summation results differ by a factor of 2 from a rough estimate obtained by limiting the intermediate state summation to one bound state. Higher order electron correlation effects are also examined.

Pindzola, M. S.

1977-01-01

449

Observation of excited ?(b)(0) baryons.  

PubMed

Using pp collision data corresponding to 1.0 fb(-1) integrated luminosity collected by the LHCb detector, two narrow states are observed in the ?(b)(0)?(+)?(-) spectrum with masses 5911.97±0.12(stat)±0.02(syst)±0.66(?(b)(0) mass) MeV/c(2) and 5919.77±0.08(stat)±0.02(syst)±0.66(?(b)(0) mass) MeV/c(2). The significances of the observations are 5.2 and 10.2 standard deviations, respectively. These states are interpreted as the orbitally excited ?(b)(0) baryons, ?(b)(*0)(5912) and ?(b)(*0)(5920). PMID:23215180

Aaij, R; Abellan Beteta, C; Adametz, A; Adeva, B; Adinolfi, M; Adrover, C; Affolder, A; Ajaltouni, Z; Albrecht, J; Alessio, F; Alexander, M; Ali, S; Alkhazov, G; Alvarez Cartelle, P; Alves, A A; Amato, S; Amhis, Y; Anderson, J; Appleby, R B; Aquines Gutierrez, O; Archilli, F; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Bachmann, S; Back, J J; Balagura, V; Baldini, W; Barlow, R J; Barschel, C; Barsuk, S; Barter, W; Bates, A; Bauer, C; Bauer, Th; Bay, A; Beddow, J; Bediaga, I; Belogurov, S; Belous, K; Belyaev, I; Ben-Haim, E; Benayoun, M; Bencivenni, G; Benson, S; Benton, J; Bernet, R; Bettler, M-O; van Beuzekom, M; Bien, A; Bifani, S; Bird, T; Bizzeti, A; Bjørnstad, P M; Blake, T; Blanc, F; Blanks, C; Blouw, J; Blusk, S; Bobrov, A; Bocci, V; Bondar, A; Bondar, N; Bonivento, W; Borghi, S; Borgia, A; Bowcock, T J V; Bozzi, C; Brambach, T; van den Brand, J; Bressieux, J; Brett, D; Britsch, M; Britton, T; Brook, N H; Brown, H; Büchler-Germann, A; Burducea, I; Bursche, A; Buytaert, J; Cadeddu, S; Callot, O; Calvi, M; Calvo Gomez, M; Camboni, A; Campana, P; Carbone, A; Carboni, G; Cardinale, R; Cardini, A; Carson, L; Carvalho Akiba, K; Casse, G; Cattaneo, M; Cauet, Ch; Charles, M; Charpentier, Ph; Chen, P; Chiapolini, N; Chrzaszcz, M; Ciba, K; Cid Vidal, X; Ciezarek, G; Clarke, P E L; Clemencic, M; Cliff, H V; Closier, J; Coca, C; Coco, V; Cogan, J; Cogneras, E; Collins, P; Comerma-Montells, A; Contu, A; Cook, A; Coombes, M; Corti, G; Couturier, B; Cowan, G A; Craik, D; Currie, R; D'Ambrosio, C; David, P; David, P N Y; De Bonis, I; De Bruyn, K; De Capua, S; De Cian, M; De Miranda, J M; De Paula, L; De Simone, P; Decamp, D; Deckenhoff, M; Degaudenzi, H; Del Buono, L; Deplano, C; Derkach, D; Deschamps, O; Dettori, F; Dickens, J; Dijkstra, H; Diniz Batista, P; Domingo Bonal, F; Donleavy, S; Dordei, F; Dosil Suárez, A; Dossett, D; Dovbnya, A; Dupertuis, F; Dzhelyadin, R; Dziurda, A; Dzyuba, A; Easo, S; Egede, U; Egorychev, V; Eidelman, S; van Eijk, D; Eisele, F; Eisenhardt, S; Ekelhof, R; Eklund, L; El Rifai, I; Elsasser, Ch; Elsby, D; Esperante Pereira, D; Falabella, A; Färber, C; Fardell, G; Farinelli, C; Farry, S; Fave, V; Fernandez Albor, V; Ferro-Luzzi, M; Filippov, S; Fitzpatrick, C; Fontana, M; Fontanelli, F; Forty, R; Francisco, O; Frank, M; Frei, C; Frosini, M; Furcas, S; Gallas Torreira, A; Galli, D; Gandelman, M; Gandini, P; Gao, Y; Garnier, J-C; Garofoli, J; Garra Tico, J; Garrido, L; Gascon, D; Gaspar, C; Gauld, R; Gauvin, N; Gersabeck, M; Gershon, T; Ghez, Ph; Gibson, V; Gligorov, V V; Göbel, C; Golubkov, D; Golutvin, A; Gomes, A; Gordon, H; Grabalosa Gándara, M; Graciani Diaz, R; Granado Cardoso, L A; Graugés, E; Graziani, G; Grecu, A; Greening, E; Gregson, S; Grünberg, O; Gui, B; Gushchin, E; Guz, Yu; Gys, T; Hadjivasiliou, C; Haefeli, G; Haen, C; Haines, S C; Hampson, T; Hansmann-Menzemer, S; Harnew, N; Harnew, S T; Harrison, J; Harrison, P F; Hartmann, T; He, J; Heijne, V; Hennessy, K; Henrard, P; Hernando Morata, J A; van Herwijnen, E; Hicks, E; Hoballah, M; Hopchev, P; Hulsbergen, W; Hunt, P; Huse, T; Huston, R S; Hutchcroft, D; Hynds, D; Iakovenko, V; Ilten, P; Imong, J; Jacobsson, R; Jaeger, A; Jahjah Hussein, M; Jans, E; Jansen, F; Jaton, P; Jean-Marie, B; Jing, F; John, M; Johnson, D; Jones, C R; Jost, B; Kaballo, M; Kandybei, S; Karacson, M; Karbach, T M; Keaveney, J; Kenyon, I R; Kerzel, U; Ketel, T; Keune, A; Khanji, B; Kim, Y M; Knecht, M; Kochebina, O; Komarov, I; Koopman, R F; Koppenburg, P; Korolev, M; Kozlinskiy, A; Kravchuk, L; Kreplin, K; Kreps, M; Krocker, G; Krokovny, P; Kruse, F; Kruzelecki, K; Kucharczyk, M; Kudryavtsev, V; Kvaratskheliya, T; La Thi, V N; Lacarrere, D; Lafferty, G; Lai, A; Lambert, D; Lambert, R W; Lanciotti, E; Lanfranchi, G; Langenbruch, C; Latham, T; Lazzeroni, C; Le Gac, R; van Leerdam, J; Lees, J-P; Lefèvre, R; Leflat, A; Lefrançois, J; Leroy, O; Lesiak, T; Li, L; Li, Y; Li Gioi, L; Lieng, M; Liles, M; Lindner, R; Linn, C; Liu, B; Liu, G; von Loeben, J; Lopes, J H; Lopez Asamar, E; Lopez-March, N; Lu, H; Luisier, J; Mac Raighne, A; Machefert, F; Machikhiliyan, I V; Maciuc, F; Maev, O; Magnin, J; Malde, S; Mamunur, R M D; Manca, G; Mancinelli, G; Mangiafave, N; Marconi, U; Märki, R; Marks, J; Martellotti, G; Martens, A; Martin, L; Martín Sánchez, A; Martinelli, M; Martinez Santos, D; Massafferri, A; Mathe, Z; Matteuzzi, C; Matveev, M; Maurice, E; Maynard, B; Mazurov, A; McCarthy, J; McGregor, G; McNulty, R; Meissner, M; Merk, M; Merkel, J; Milanes, D A; Minard, M-N; Molina Rodriguez, J; Monteil, S; Moran, D; Morawski, P; Mountain, R; Mous, I; Muheim, F; Müller, K; Muresan, R; Muryn, B; Muster, B; Mylroie-Smith, J; Naik, P; Nakada, T; Nandakumar, R; Nasteva, I; Needham, M; Neufeld, N; Nguyen, A D; Nguyen-Mau, C; Nicol, M; Niess, V; Nikitin, N; Nikodem, T; Nomerotski, A; Novoselov, A; Oblakowska-Mucha, A

2012-10-26

450

A numerical method to model excitable cells.  

PubMed Central

We have extended a fast, stable, and accurate method for the numerical solution of cable equations to include changes in geometry and membrane properties in order to model a single excitable cell realistically. In addition, by including the provision that the radius may be a function of distance along an axis, we have achieved a general and powerful method for simulating a cell with any number of branched processes, any or all of which may be nonuniform in diameter, and with no restriction on the branching pattern. PMID:656539

Joyner, R W; Westerfield, M; Moore, J W; Stockbridge, N

1978-01-01

451

PHOTOSYNTHESIS: Coherent Excitation in the Antenna Complex  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Photosynthesis is key to life on Earth, and the exact mechanisms by which light is harvested and converted into chemical energy remain the subject of intense research. Orrit (page 349) discusses the implications of a single molecule study by van Oijen et al. (page 400), which sheds light on the delocalization of excited states in the antenna complex that harvests and funnels light energy into the reaction center. Subtle structural distortions can also be discerned from the optical spectra, complementing information obtained from x-ray structures.

M. Orrit (CNRS and Université Bordeaux;)

1999-07-16

452

Near-threshold excitation of continuum resonances  

NASA Astrophysics Data System (ADS)

We examine the excitation of continuum-state resonances close to the threshold, paying particular attention to the breakdown of the Markov approximation and the consequences of this for initial-state time dependences and final-state spectra. Several theoretical dressed-state alternative descriptions are analyzed and compared: the nonperturbative coupling of a discrete state to a structured continuum with a threshold, the complete Fano diagonalization of the interacting system, and finally a partial diagonalization of the bound-state couplings to reveal the origin of dressed-state stabilization and partial decay suppression observed in this model.

Piraux, B.; Bhatt, R.; Knight, P. L.

1990-06-01

453

Effects of ionizing radiation on hippocampal excitability  

SciTech Connect

Ionizing radiation causes striking changes in hippocampal activity in vivo. Changes in neuronal firing patterns and spiking activity in electroencephalographic recordings appear at doses as low as 4 Gy. Accompanying exposure to ionizing radiation is a breakdown in blood brain barrier and a decrease in cerebral blood flow. In an effort to define the mechanisms of radiation damage to neuronal excitability, without these complicating factors, the effects of radiation on neuronal activity in hippocampal slices were investigated. Damage is likely to result from generation of free radicals. Since peroxide mixed with iron produces hydroxyl free radicals through the Fenton reaction, peroxidative damage was evaluated on hippocampal slices for comparison.

Pellmar, T.C.; Tolliver, J.M.

1986-01-01

454

Science Instructors' Views of Science and Nature of Science  

ERIC Educational Resources Information Center

This qualitative study examined how college science faculty who teach introductory level undergraduate science courses including the fields of chemistry, biology, physics, and earth science, understand and define science and nature of science (NOS). Participants were seventeen science instructors from five different institutions in the…

Karakas, Mehmet

2011-01-01

455

The sciences of science communication  

PubMed Central

The May 2012 Sackler Colloquium on “The Science of Science Communication” brought together scientists with research to communicate and scientists whose research could facilitate that communication. The latter include decision scientists who can identify the scientific results that an audience needs to know, from among all of the scientific results that it would be nice to know; behavioral scientists who can design ways to convey those results and then evaluate the success of those attempts; and social scientists who can create the channels needed for trustworthy communications. This overview offers an introduction to these communication sciences and their roles in science-based communication programs. PMID:23942125

Fischhoff, Baruch

2013-01-01

456

Personalizing Science  

ERIC Educational Resources Information Center

Science teachers are aware of many social issues that intersect with science. These socio-scientific issues (SSIs) are "open-ended problems without clear-cut solutions [that] can be informed by scientific principles, theories, and data, but…cannot be fully determined by [them]" (Sadler 2011, p. 4). This article describes the SSI lessons…

Danielowich, Robert M.

2014-01-01

457

Science Notes.  

ERIC Educational Resources Information Center

Presents 31 science activities for use with high school or college science classes. Topics included are: chromatography, ecology, invertebrates, enzymes, genetics, botany, creep, crystals, diffusion, computer interfaces, acid rain, teaching techniques, chemical reactions, waves, electric fields, rainbows, electricity, magnetic fields, and a Pitot…

Murray, A. J. S.; And Others

1988-01-01

458

Soundsational Science  

ERIC Educational Resources Information Center

The science of sound helps students learn that sound is energy traveling in waves as vibrations transfer the energy through various media: solids, liquids, and gases. In addition to learning about the physical science of sound, students can learn about the sounds of different animal species: how sounds contribute to animals' survival, and how…

Carrier, Sarah J.; Scott, Catherine Marie; Hall, Debra T.

2012-01-01

459

Deconstructing Science  

ERIC Educational Resources Information Center

In this paper I expand on the premises of Jesse Bazzul's thesis in his paper, "Neoliberal ideology, global capitalism, and science education: engaging the question of subjectivity," exploring the implications of the ideologies within the culturally emerging logic of science exposes the incommensurability of intents and purposes in its methods and…

Trifonas, Peter Pericles

2012-01-01

460

Why Science?  

ERIC Educational Resources Information Center

This article presents people from many walks of life, including some well-known names, who share their views about science. Adam Hart-Davis, who studied chemistry at university and is now an author, photographer, historian and broadcaster, explains why science cannot start too soon. Lis Nairn, Manager, Stratigraphy, with Fugro Robertson Ltd (Oil…

Primary Science Review, 2006

2006-01-01

461

Legendary Science.  

ERIC Educational Resources Information Center

Spiders and insects are studied in both Navajo Studies and science classes at a middle school in New Mexico. In Navajo Studies, students learn the names of ground-dwelling insects and the connection between those names and traditional Navajo stories. In science class, students study arthropods to illustrate taxonomy of life, trophic and biological…

O'Keefe, William A.; Joe, Jimson

1998-01-01

462

Science Portal  

NSDL National Science Digital Library

The Australian governmental Web site, Science Portal delivers science information and services to industry, investors, and the research community. The site allows visitors to find relevant links in their field from all of Australia's research and research-related organization Web sites. The portal can be searched or browsed by various research topics including directories and databases, policy, research grants, and more.

463

Force Sensor Characterization Under Sinusoidal Excitations  

PubMed Central

The aim in the current work is the development of a method to characterize force sensors under sinusoidal excitations using a primary standard as the source of traceability. During this work the influence factors have been studied and a method to minimise their contributions, as well as the corrections to be performed under dynamic conditions have been established. These results will allow the realization of an adequate characterization of force sensors under sinusoidal excitations, which will be essential for its further proper use under dynamic conditions. The traceability of the sensor characterization is based in the direct definition of force as mass multiplied by acceleration. To do so, the sensor is loaded with different calibrated loads and is maintained under different sinusoidal accelerations by means of a vibration shaker system that is able to generate accelerations up to 100 m/s2 with frequencies from 5 Hz up to 2400 Hz. The acceleration is measured by means of a laser vibrometer with traceability to the units of time and length. A multiple channel data acquisition system is also required to simultaneously acquire the electrical output signals of the involved instrument in real time. PMID:25290287

Medina, Nieves; de Vicente, Jesús

2014-01-01

464

Dual excitation acoustic paramagnetic logging tool  

DOEpatents

New methods and apparatus are disclosed which allow measurement of the presence of oil and water in geological formations using a new physical effect called the Acoustic Paramagnetic Logging Effect (APLE). The presence of petroleum in formation causes a slight increase in the earth's magnetic field in the vicinity of the reservoir. This is the phenomena of paramagnetism. Application of an acoustic source to a geological formation at the Larmor frequency of the nucleons present causes the paramagnetism of the formation to disappear. This results in a decrease in the earth's magnetic field in the vicinity of the oil bearing formation. Repetitively frequency sweeping the acoustic source through the Larmor frequency of the nucleons present (approx. 2 kHz) causes an amplitude modulation of the earth's magnetic field which is a consequence of the APLE. The amplitude modulation of the earth's magnetic field is measured with an induction coil gradiometer and provides a direct measure of the amount of oil and water in the excitation zone of the formation. The phase of the signal is used to infer the longitudinal relaxation times of the fluids present, which results in the ability in general to separate oil and water and to measure the viscosity of the oil present. Such measurements may be performed in open boreholes and in cased well bores. The Dual Excitation Acoustic Paramagnetic Logging Tool employing two acoustic sources is also described. 6 figs.

Vail, W.B. III.

1989-02-14

465

Universality of plasmon excitations in Dirac semimetals  

E-print Network

The recent experimental discovery of ${\\rm Cd_3 As_2}$ and ${\\rm Na_3 Bi}$ Dirac semimetals enables the study of the properties of chiral quasi-particles in three spatial dimensions. As demonstrated by photoemission, Dirac semimetals are characterized by a linear dispersion relation for fermion quasi-particles, and thus represent three dimensional analogs of graphene. While the distinctive behavior of chiral fermions (e.g. Klein tunneling) is already evident in two dimensional graphene, the physics of chirality in three dimensions opens a number of new possibilities. In this paper we investigate the properties of the collective plasmon excitations in Dirac semimetals by using the methods of relativistic field theory. We find a strong and narrow plasmon excitation whose frequency is in the terahertz (THz) range which may be important for practical applications. The properties of the plasmon appear universal for all Dirac semimetals, due to the large degeneracy of the quasi-particles and the small Fermi velocity, $v_F \\ll c$. This universality is closely analogous to the phenomenon of "dimensional transmutation", that is responsible for the emergence of dimensionful scales in relativistic field theories such as Quantum Chromodynamics, the modern theory of nuclear physics.

Dmitri E. Kharzeev; Robert D. Pisarski; Ho-Ung Yee

2014-12-18

466

Dual excitation acoustic paramagnetic logging tool  

DOEpatents

New methods and apparatus are disclosed which allow measurement of the presence of oil and water in gelogical formations using a new physical effect called the Acoustic Paramagnetic Logging Effect (APLE). The presence of petroleum in formation causes a slight increase in the earth's magnetic field in the vicinity of the reservoir. This is the phenomena of paramagnetism. Application of an acoustic source to a geological formation at the Larmor frequency of the nucleous present causes the paramagnetism of the formation to disappear. This results in a decrease in the earth's magnetic field in the vicinity of the oil bearing formation. Repetitively frequency sweeping the acoustic source through the Larmor frequency of the nucleons present (approx. 2 kHz) causes an amplitude modulation of the earth's magnetic field which is a consequence of the APLE. The amplitude modulation of the earth's magnetic field is measured with an induction coil gradiometer and provides a direct measure of the amount of oil and water in the excitation zone of the formation. The phase of the signal is used to infer the longitudinal relaxation times of the fluids present, which results in the ability in general to separate oil and water and to measure the viscosity of the oil present. Such measurements may be preformed in open boreholes and in cased well bores. The Dual Excitation Acoustic Paramagnetic Logging Tool employing two acoustic sources is also described.

Vail, III, William B. (Bothell, WA)

1989-01-01

467

Excitation spectrum of multiferroics at finite temperatures  

NASA Astrophysics Data System (ADS)

A systematic microscopic theory of the magnetoelectric (ME) effect in multiferroic materials with well-separated phase-transition temperatures is presented. Whereas the ferroelectric subsystem is described by an Ising model in a transverse field, the magnetic one is characterized by the Heisenberg model with Dzyaloshinski-Moriya interaction (DMI). The symmetry-allowed quartic coupling between both subsystems, and the application of a Green’s function technique in a dynamical mean-field approximation, exhibit the calculation of the elementary excitations analytically, which are mutually influenced by the respective other subsystem. The magnetic excitation is a Goldstone mode, while the ferroelectric dispersion relation shows a soft-mode-like behavior. We find the macroscopic polarization and the transverse magnetization in a broad temperature interval up to the corresponding phase-transition temperatures (type-I multiferroics). Due to the DMI, the system offers different spiral structures, which are incorporated into the model by using a transformation of the underlying spin operators into a representation without a fixed quantization axis. The polarization increases at the magnetic phase-transition temperature, and is also enhanced by increasing the ME coupling strength as well as the DMI. We demonstrate likewise the variation of the spin-wave dispersion relation with the ME coupling strength and the DMI. As a consequence, the macroscopic magnetization is enhanced with increasing coupling.

Michael, Thomas; Trimper, Steffen

2011-04-01

468

Topological excitations in a kagome magnet.  

PubMed

Chirality--that is, left or right handedness--is present in many scientific areas, and particularly in condensed matter physics. Inversion symmetry breaking relates chirality with skyrmions, which are protected field configurations with particle-like and topological properties. Here we show that a kagome magnet, with Heisenberg and Dzyaloshinskii-Moriya interactions, causes non-trivial topological and chiral magnetic properties. We also find that under special circumstances, skyrmions emerge as excitations, having stability even at room temperature. Chiral magnonic edge states of a kagome magnet offer, in addition, a promising way to create, control and manipulate skyrmions. This has potential for applications in spintronics, that is, for information storage or as logic devices. Collisions between these particle-like excitations are found to be elastic at very low temperature in the skyrmion-skyrmion channel, albeit without mass-conservation. Skyrmion-antiskyrmion collisions are found to be more complex, where annihilation and creation of these objects have a distinct non-local nature. PMID:25198354

Pereiro, Manuel; Yudin, Dmitry; Chico, Jonathan; Etz, Corina; Eriksson, Olle; Bergman, Anders

2014-01-01

469

Turbine blade-tip clearance excitation forces  

NASA Technical Reports Server (NTRS)

The results of an effort to assess the existing knowledge and plan the required experimentation in the area of turbine blade tip excitation forces is summarized. The work was carried out in three phases. The first was a literature search and evaluation, which served to highlight the state of the art and to expose the need for an articulated theoretical experimental effort to provide not only design data, but also a rational framework for their extrapolation to new configurations and regimes. The second phase was a start in this direction, in which several of the explicit or implicit assumptions contained in the usual formulations of the Alford force effect were removed and a rigorous linearized flow analysis of the behavior of a nonsymmetric actuator disc was carried out. In the third phase a preliminary design of a turbine test facility that would be used to measure both the excitation forces themselves and the flow patterns responsible for them were conducted and do so over a realistic range of dimensionless parameters.

Martinez-Sanchez, M.; Greitzer, E. M.

1985-01-01

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